THE 
VIARINERS'    HANDBOOK 

A  CONVENIENT  REFERENCE  BOOK 


ivigators,  Yachtsmen,  and  Seamen  of  all  classes,  and 
tor  all  persons  interested  in  the  Navy,  the 
Merchant  Marine,  and  Nautical 
Matters  generally 


International  Correspondence  Schools 

SCRANTON,  Pa. 


I  St  Edition,  1 3th  Thousand,  3d  Impression 


SCRANTON,  PA. 
INTERNATIONAL  TEXTBOOK  COMPANY 


Copyright,  1906.  by 

International  Textbook  Company 

Entered  at  Stationers'  Hall.  London 

All  Rights  Reserved 


FKINTBD  IN  THB  UNITED  STATES 


PREFACE 


This  handbook  is  intended  as  a  book  of 
■reference  to  the  young  men  in  the  merchant 
narine,  as  well  as  to  those  in  the  naval  serv^ice. 
vVhile  the  treatment  of  some  of  the  subjects 
ncluded  is  necessarily  brief,  the  information 
given  should  nevertheless  prove  very  useful  and 
create  a  desire  for  further  study  and  investi- 
igation. 

Ambitious  seamen  trying  to  fit  themselves 
for  examination  to  higher  rank  in  either  service 
are  often  embarrassed  by  a  lack  or  insufficient 
knowledge  of  logarithms;  hence,  we  have  incor- 
porated a  thorough  and  comprehensive  article 
lOn  that  subject  accompanied  by  tables  of  com- 
;nion  logarithms. 

In  the  subject  of  navigation,  terrestrial  and 
celestial,  are  included  only  the  standard  methods 
practiced  by  the  up-to-date  navigator,  and  for 
this  reason  the  book  should  be  of  value  to  the 
student,  as  well  as  to  the  navigating  officer.  The 
treatment  of  these  subjects  does  not  consist 
:merely  of  definitions  of  terms,  but  rules,  formulas, 
and  directions  are  given  for  each  method,  fol- 
lowed in  every  case  by  examples  and  carefully 
•worked  out  solutions  illustrating  the  process  or 


hr  PREFACE 

method  explained.  Of  equal  importance  to  the 
student  and  the  professional  man  should  be  the 
articles  dealing  with  deviation,  the  compensation 
of  compasses,  and  the  manipulation  of  rope. 
All  problems  appearing  throughout  the  book 
involving  elements  of  time  are  worked  out  for 
values  given  in  the  Nautical  Almanac  of  1904. 

It  is  hoped  that  the  subject  of  the  United 
States  Navy  and  matters  relating  to  the  naval 
service  will  prove  valuable  and  instructive  not 
only  to  men  directly  connected  w4th  the  Navy, 
but  also  to  that  great  auxiliary  of  the  Navy,  the 
officers  and  men  of  the  Merchant  Marine,  and 
that  it  will,  in  a  measure,  tend  to  draw  closer 
the  ties  now  existing  between  the  two  branches. 

This  handbook  was  prepared  under  the 
supervision  of  E.  K.  Roden,  Principal  of  our 
School  of  Navigation. 

International  Correspondence  Schools. 


INDEX 


Additional  rewards  in  the 

Navy,  160. 
Addition  of  decimals,  15. 

of  fractions,  13. 
Administrative  bureaus  of 

Navy,  150. 
Agonic  lines,  70. 
Air  flask  of  torpedo,  225. 
Alternation,  17. 
Altitude,    Meridian,   of    a 
star.  130. 

Meridian,  of  the  moon, 
131. 

Meridian,  of  the  sun,  129. 

Observed,  121. 

Parallax  in,  123. 

True,  121. 
Altitudes,    Correction    of 
128. 

Equal,  near  noon,  138. 
Ammunition  car,  211, 

Fixed,  188. 
Amplitude,  Compass,  122. 

True,  122. 
Aneroid  barometer.  Indica- 
tions  of   weather  by, 
283. 
Angle,  Cosecant  of,  65. 

Cosine  of,  64. 

Cotangent  of,  64. 

Hour,  122. 

Secant  of,  65. 

Sine  of,  64. 

Spherical.  92. 

Tangent  of.  64. 
Angles.  Danger.  115. 

Measure  of,  2. 
Angular  distance,  119. 
Annual  parallax,  123. 
Any  root.  Extracting,  19. 
Apparent  solar  day,  126. 
Application  for  admission 
to  citizenship,  321. 


Application  of  trigonome- 
try in  practice,  66. 
Apprentices,  Naval,  161. 
Approaching    or    receding 
of    storm    center.    To 
find,  288. 
Arc,  Complement  of,  64. 

Supplement  of,  64. 
Arcs,  Measure  of,  2. 
Aries,  First  point  of,  119. 
Arithmetic,  13. 
Armor.  Compound.  250. 

Harveyized,  250. 

Kruppized,  253. 

piercing  shells,  204. 

shelf,  250. 
Armored  cruisers,  174. 

decks,  250. 
Arrangement  of  code  book. 
International    signals, 
293. 
Artificer  branch,  157. 
Artificial  magnets,  68. 
Ascension.  Right,  122. 
Asteroids,  124. 
Astronomical  dav,  127. 

terms,  119. 
Attraction   and  repxilsion. 
Magnetic.  69. 

Local,  72. 
Automatic  guns,  188. 
Autumnal  equinox,  119. 
Avoirdupois  weight,  2. 
Axis,  Magnetic,  69. 

of  the  earth,  92. 
Azimuth,  Compass,  122. 

True,  121. 


Band.  Rotating.  198. 

slope,  198. 
Bands,  Locking.  196. 
Bar.  Flinders,  77, 

keel.  239. 


INDEX 


Barge  Navy,  185. 
Barometer,  aneroid. 
Weather     indications 
by.  283. 

mercurial,  Weather  indi- 
cations by,  281. 
Base  and  rate,  To  find  per- 
centage, 22. 

fuses,  208. 
Battle  drill,  168. 

ships,  174. 
Bearing,    Four-point,   111. 

of  an  object,  93. 
Bearings,  Bow,  110. 

Cross,  109. 

of  same  object  and  dis- 
tance run,  111. 

reciprocal, Simultaneous, 
79. 
Belaying  of  ropes,  281. 
Bends  and  hitches,  277. 

and  splices,  270. 
Bend,  Sheet,  277. 
Bilge  keelson,  240. 
Billet,  Station,  169. 
Black  powder,  218. 
Blackwall  hitch,  277, 
Blasting  gelatine,  217. 
Blocks,  Breech.  198. 
Blue  polarity,  69. 
Boats,  Man-of-war.  185. 

Navy,  Rigs  of,  185. 

Torpedo,  179. 

torpedo,  Importance  of, 
233. 

Whale,  185. 
Boatswain's  mates,  Duties 

of,  162. 
Bore,  Rifling  the,  196. 
Bottom,  Double,  244. 
Bow-bearings,  110. 
Bowline    How  made,  277. 
Branch,  Artificer.  157. 

hydrographic  offices, 292. 

Messmen,  158. 

Seamen,  156. 

Special,  158. 
Breaking  strain  of  manila 

rope,  266. 
Breasthooks,  242. 
Breathing,  To  produce. 316. 


Breech  block,  198. 

block,  The  Driggs- 
Schroeder,  200. 

block,  The  Welin.  199. 

closure,  Hotchkiss,  199. 

loading  gun,  187. 

mechanism,      Principles 
of,  200. 

mechanisms  of  guns,  198. 

plug.  The  Elswick,  199. 
Briggs  logarithms,  27. 
Brown  powder,  219. 
Bugle  calls,  185. 
Built-up  gun,  187. 
Bulkhead,  Collision,  246. 
Bulkheads,  245. 
Bureau,  Chief  of,  150. 
Bureaus,      Administrative 
naval,  150. 


Cable  and  hawser,  263. 
Calls,  Bugle,  185. 
Capacity  and  volume,  Mea- 
sures of,  9. 
Capped  projectiles,  205. 
Car,  Ammunition,  211. 
Carbodynamite,  216. 
Card,  Compass,  85. 
Carriage  of  a  gun,  208. 
Carrick  bend,  Double,  277. 
Cast-steel    wire    ropes. 

Strength  of,  269. 
Celestial  equator,  119. 

latitude,  124. 

longitude,  124. 

longitude.  Circles  of,  123. 

meridians.  120. 

navigation,  119. 

poles.  119. 

sphere,  119. 
Center  keelson,  240. 

of    hurricane.    To    find, 
287. 
Chain     splice.    To    make, 

274. 
Chamber,  Immersion,  226. 

slope,  198. 
Chaplains  in  Navy^  152. 
Characteristic,  28. 
Charge.  Ignition.  202. 


INDEX 


Chart,     Mercator's,     Con- 
struction of,  105. 
Charts,  foreign,  Meridians 
of,  117. 
foreiRn,    Soundings    on, 

118. 
Great-circle,  109. 
Chief    of    bvireau,    Navy, 

150. 
Chinese     naturalization 

laws.  322. 
Circle,  23. 
Great,  92. 
Small,  92. 
Circles,  Hour,  120. 

of     celestial     longitude, 
123. 
Circular  ring,  27. 
Citizen,  Declaration  of  in- 
tention    to     become, 
320. 
Citizenship,  Application  to 
receive,  321. 
Conditions  for,  321. 
Citizens,  naturalized.  Pro- 
tection abroad  to,  323. 
Civil  day,  127. 
Classification    of    enlisted 
men,  154. 
of  guns,  187. 
of  war  ships,  173. 
Coast  navigation.  Methods 

in,  109. 
Cocoa  powder,  220. 
Code  book  of  International 
signals.    Arrangement 
of,  293. 
of  signals,  International, 

293. 
signals,  International, 
selected,  294. 
Coefficient  B,  To  compen- 
sate, 76. 
C,  To  compensate,  75. 
of  fineness,  255. 
Coefficients,  Magnetic,  74. 
Coir  rope,  262. 
Collision  bulkhead,  246. 
Combination  primer^  203. 
Commerce-dest  roying 
cruiser,  174. 


Commissarv    steward. 

Duties  of,  163. 
Commissioned  officers.  163. 
Common  fractions,  13. 
logarithms.  Explanation 
of,  27. 
Common  logarithms.  Table 
of,  46. 
shells,  204. 
Compartments,     Water- 
tight, 245. 
Compass  amplitude,  122. 
azimuth,  122. 
card,  85. 
course,  83. 

course,  To  find  true,  80 
Deviation  of,  71. 
error,  68. 
management.     Remarks 

on,  81. 
points    in    various    lan- 
guages, 88. 
points.  Table  of,  86. 
points  to  degrees,  86. 
Compasses,   Compensation 

of,  73. 
Compensation  of  coefficient 
B,  76. 
of  coefficient  C,  75. 
of  compasses,  73. 
of  quadrantal  deviation, 
74. 
Complement  of  an  arc,  64. 
Completed       warships, 
Number  of,  309. 
warships.    Tonnage    of, 
310. 
Components,  Magnetic,  70. 
Composite  sailing,  94. 
Composition  of  gunpowder, 
218. 
of  steel,  192. 
of  the  hull,  238. 
Compound  armor,  250. 
fractions,  Reduction  of; 

to  simple,  14. 
proportion,  17. 
Conditions  for  citizenship, 

321. 
Conjunction,  Inferior.  124. 
Superior,  124. 


Vlll 


INDEX 


Constants,  Table  of,  255. 
Constructing   a    Mercator- 

ial  chart,  105. 
Construction,  gun,  Princi- 
ples of.  189. 
Cordite  powder,  222. 
Corps,  Medical,  151. 

Pav,  152. 

Staff,  151. 
Correction  of  altitudes,  12-8. 

of  courses,  83. 
Cosecant  of  an  angle,  65. 
Cosine  of  an  angle,  64. 
Cotangent  of  an  angle,  64. 
Course,  Compass,  83. 

Final,  94. 

Initial,  94. 

made  good,  93. 

True,  83. 
Courses,  Correction  of,  83. 
Coxswains,  Duties  of,  162. 
Crew,  Organization  of,  in 

Navy,  166. 
Cross-bearings,  108. 

hitch,  277. 
Cruiser,  Commerce- des- 
troying, 174. 
Cruisers  and  gunboats, 
179. 

Armored,  174. 

Protected,  179. 
Cubic  measure,  1. 
Curve,  Loxodromic,  93. 
Custom-hotise  fees,  323. 
Cutters,  Navy,  185. 
Cyclones  or  hurricanes,  284. 
Cvlinder,  26. 

Frustum  of,  26, 


Daily   routine  in   port  of 

the  Navy,  169. 
Danger  angle.  Horizontal, 
116. 
angles,  115. 
angle.  Vertical,  116. 
Dangerous     semicircle     in 

hurricane,  284. 
Date,  Greenwich,  128. 
Day.  Apparent.  126. 
Astronomical,  127. 


Day,  Civil,  127. 
Mean,  126. 
Sidereal.  127. 
Day's  work,  100. 
Dead  reckoning,  94. 

reckoning.  Formulas  for 
95. 
De   Bange   system  of  gas 

checking,  201. 
Decimal  fractions,  15. 
Decimals,  Addition  of,  15. 
Division  of,  16. 
Multiplication  of,  16. 
Subtraction  of.  15. 
to  fractions,  14. 
Deck,  Armored,  250. 
Officer  of  the,  166. 
stringer,  241. 
Declaration  of  intention  to 

become  citizen,  320. 
Declination,  122. 

Parallels  of.  122. 
Definition  of  fleet,  184. 
of  flotilla,  184. 
of  latitude,  92. 
of  longitude,  92. 
of  squadron,  184. 
Definitions,  Astronomical, 
119. 
relating   to    magnetism, 
68. 
Degrees  to  compass  points. 

Table,  86. 
Delayed-action  fuses,  208. 
Denominator.  13. 
Departure,  93. 
Description  of  storm  cen- 
ter, 289. 
Destroyers,  Torpedo-boat, 

184. 
Determination  of  latitude, 
129. 
of  longitude,  135. 
Deviation  of  the  compass, 
71. 
Quadrantal,  72. 
quadrantal,  To  compen- 
sate. 74. 
Semicircular.  72. 
To  swing  a  ship  for,  79. 
Diameter  of  a  sphere,  91. 


INDEX 


Difference  of  latitude,  93. 

of  latitude,    Meridional, 
94. 

of  longitude,  93. 
Dimensions  of  notable 

steamships,  314. 
Dingies,  Navy,  185. 
Dip,  Magnetic,  70. 

of  the  horizon,  123. 
Director.  The  torpedo,  232. 
Displacement  and  tonnage, 
256. 

of  a  ship,  254. 
Distance,  Angular,  119. 

by  velocity  of  sound,  1 15. 

of  objects  at  sea,  114. 

Polar,  122. 

run,  93. 

Zenith,  121. 
Distances,  Sailing,  between 
principal  ports,  146. 

Table  of,  4. 
Distant  signals,  296. 

signals.  Special,  294. 
Distress  signals,  300. 
Diurnal  motion,  120. 
Division  bv  logarithms,  38. 

Gun,  167. 

of  decimals,  16. 

of  fractions,  13. 

of  fuses,  206. 

of    time    on    shipboard, 
171. 

officers,  166. 

Powder,  167. 
Double  bottom,  244. 

carrick  bend,  277. 

rule  of  three,  17. 
Driggs  fuse,  208. 

Schroeder  breech  block, 
200. 
Drill,  Battle,  168. 
Drilling,  167. 

Drowned    persons,   appar- 
ently. To  restore,  315. 
Dry  measure,  2. 
Ductility  of  steel,  192. 
Duties  of  line  officers,  165. 

Outline  of,  in  the  Navy, 
161. 
Dynamite,  216. 


Earth,  Axis  of,  92. 

Magnetic     property    of, 
69. 

Meridians  of,  92. 

Poles  of,  92. 
Ecliptic,  119. 

Obliquity  of  the,  120. 
Educational     facilities     in 

the  Navy,  164. 
Elastic    strength   of   steel, 

192. 
Electric  primer,  202. 
Elements  of  the  solar  sys- 
tem, 125. 
Ellipse,  25. 
Elongation,  126. 
Elswick  breech  plug,  199. 
Engineer  force,  167. 

officers,  166. 
English  money,  5. 
Enlisted    men.    Classifica- 
tion of,  154. 

men.  Promotion  of,  163. 

men,  Rating  of,  155. 
Enlistment  record,  169. 

Requirements  of,  155. 
Equal  altitudes  near  noon^ 
Method  of  observing,. 
138. 
Equation  of  time,  126. 
Equator,  Celestial,  119. 

Geographical,  92. 

Magnetic,  70. 
Equinoctial,  119. 

points,  119. 
Equinox,  Autumnal,  119. 

Vernal,  119. 
Equivalents,  Metric,  10. 
Error,  Heeling,  77. 

The  compass,  68. 
Etiquette    in    the     Navy, 

Notes  on,  172. 
Evolution,  19. 

by  logarithms,  42. 
Executive  officer,  165. 
Exercise  head  of  torpedo, 

225. 
Ex-Meridian    of    the    sun, 

133. 
Explosives,  214. 


IXDEX 


Exponents,  27. 
Exterior  planets,  124. 
Extracting    any    root, 

Method  of,  19. 
Eye  splice,  To  make,  274. 


Fees,  Custom-house,  323. 
Fiber  ropes,  261. 
Figure-of-eight  knot,  277. 
Final  course,  94. 
Fineness, Coefficient  of  ,255. 
Firing  of  guns,  201. 
First  points  of  Aries,  119. 
Fixed  ammunition,  188. 
Flags,   Number  used  in  a 
hoist,  294. 

Storm-warning,  301. 
Flat-plate  keel,  240. 
Fleet,  Definition  of,  184. 
Flinders  bar,  77. 
Flotilla.  Definition  of,  184. 
Force,  engineer.  Navy,  167.  ■ 
Foreign  charts,  Meridians 
of,  117. 

charts,     Soundings     on, 
118. 

measures.  Value  of,  12. 

money.  Values  of,  6. 
Formulas  for  dead  reckon- 
ing, 95. 
Four-point  bearing.  111. 

flag  signals,  294. 
Fourth  power  of  a  number, 

19. 
Fractions,  Addition  of,  13. 

Common,  13. 

Decimal,  15. 

Division  of,  13. 

Multiplication  of,  13. 

Sul)traction  of,  13. 

Table  of,  15. 

to  decimals,  14. 
Frame  bar,  238. 
Frames,  238. 
Frustum  of  cylinder,  26. 

of  prism,  26. 
Fuel  consumption  and 

speed,  259. 
Fulminate  of   mercury, 
217. 


Functions,  Trigonometric, 

65. 
Fuse,  Base,  208. 

Delayed-action,  208. 

Navy  percussion,  207. 

Percussion,  207. 

The  Driggs,  208. 

Time,  206. 
Fuses,  Division  of,  206. 

G 

Galvanized-iron  wire  rope. 
Breaking  strain  of,  267. 

steel    hawsers,  Strength 
of,  268. 
Garboard  strake,  240. 
Gas  checking,  De  Bange 
system  of,  201. 

checking,    Principle    of, 
201. 

check  slope,  198. 
Gauging,  Star,  196. 
Gear,  Obry.  229. 
Gelatine,  Blasting,  217. 
General  quarters.  168. 
Geographical  equator,  92. 
Grades  of  line  officers,  151. 
Granny  knot,  277. 
Granulation  of  powder, 

222. 
Great  circle:  92. 

circle  charts,  109. 

circle  sailing,  94. 

circle  track.  To  plot.  108. 

circle,  Verte.x  of,  94. 
Greenwich  date,  128. 
Gross  tonnage,  256. 
Gunboats  and  cruisers, 

179. 
Gun,  Breech-loading,  187. 

Built-up,  187. 

carriage,  208. 

construction.    Principles 
of,  189. 

division,  167. 

mounts,  208. 

Powder  chamber  of,  197. 

Rifled,  187. 

Screw  box  of,  197. 

steel,  191. 

steel.  Treatment  of,  193. 


INDEX 


Gun,  Top  carriage  of,  209. 
Guncotton,  216. 
Gunpowder,     Composition 

of,  218. 
Guns,  Automatic,  188. 

Breech    mechanisms   of, 
198. 

Classification  of,  187. 

Firing  of,  201. 

Layers  of,  191. 

Machine.  188. 

Manufacture  of,  194. 

Naval,  187. 

Rapid-fire,  188. 

Semiautomatic,  189. 
Gyroscope,  229. 

H 

Handling    ships   in   hurri- 
canes, 286. 
Hard  iron,  72. 
Harveyized  armor,  250. 
Hawser  and  cable,  263. 
Hawsers,  galvanized-steel, 
Strength  of,  268. 
steel,  for  heavy  towing, 
Strength  of,  268. 
Heeling  error,  77. 
Height,   Metacentric,  237. 
Hellhoffite,  217. 
Hemisphere,  92. 
Hemp  ropes,  261. 
Hitch,  Blackwall,  277. 
Hitches  and  bends,  277. 
Horizon,  Dip  of,  123. 
Rational,  120. 
Sea,  121. 
Sensible,  120. 
True,  120. 
Horizontal    and    vertical 
iron,  72. 
danger  angle,  116. 
Horsepower,  Indicated, 
254. 
Rule  for  finding,  254. 
Hotchkiss  breech  closure, 

199. 
Hour  angle,  122. 

circles,  120. 
Hull,   Composition  of  the 
238. 


Hurricanes,     Handling    of 
ships  in,  286. 

Motion  of.  284. 

or  cyclones,  284. 

To  find  center  of,  287. 
Hurricane  warning  signals, 

301. 
Hydraulic  rammer,  211. 
Hydrographic  offices,  292. 
Hydrostatic  piston,  226. 
Hyperbolic  logarithms,  27. 


Ignition  charge,  202. 
Immersion   chamber.   226. 
Indicated  horsepower,  254. 
Indications    of    typhoons, 
289. 
of    weather   by   aneroid 

barometer,  283. 
of   weather   by   appear- 
ance of  sky,  283. 
of  weather  by  mercurial 
barometer,  281. 
Indicator,  254. 
Induction,   Magnetic,   70. 
Inferior  conjunction,    124. 
Initial  course,  94. 

tensions     in     gun     con- 
struction, 189. 
Insignia  of  naval  officers, 

153. 
Interior  planets,  124. 
International  code  of  sig- 
nals, 293. 
code  signals,  Selected, 

294. 
signals,  Arrangement  of 
code  book,  293. 
Inversion,  17. 
Involution,  18. 

by  logarithms,  40. 
Iron,  Hard,  72. 
Soft,  72. 
Vertical  and  horizontal, 

72. 
wire     rope,     galvanized, 
Breaking  strain  of,  267. 
Isoclinic  lines,  70. 
Isodynamic  lines,  71. 
Isogonic  lines,  70. 


IXDEX 


K 

Keel,  Bar,  239. 

Different  tvpes  of,  241. 

Flat-plate,  240. 

Side-bar,  240. 
Keelson,  BilK'e,  240. 

Center,  240. 

Side,  240. 
Kilometers      to      nautical 

miles,  11. 
Knot,  Figure-of-eight,  277. 

Granny,  277. 
Knot,  Reef,  277. 
Kruppized  armor,  253. 


Largest     steamship     com- 
panies. Table  of,  312, 
Latitude,  Celestial,  124. 

Definition  of,  92. 

determinations,  129. 

Difference  of,  93. 

Middle,  93. 

Parairels  of,  92. 
Latitudes.   Table   of,    104. 
Launches,  Navy,  185. 

Steam,  185. 
Launching    tubes    of    tor- 
pedoes, 231. 
Laws,  U.S.  naturalization, 

320. 
Layers  of  guns,  191. 
Leeway,  83. 

Length,  Measures  of,  9. 
Life-saving  signals,  302. 
Lights  in   different  lan- 
guages, 118. 
Linear  measure,  1. 
Line  officers,  151. 

officers  and  their  duties, 
165. 

officers,  Grades  of,   151. 

officers.  Number  of,  152. 

of  position,  142. 

Sumner,  142. 
Lines,  Agonic,  70. 

Isoclinic,  70. 

Isodynamic,  71. 

Isogonic,  70. 
Liquid  measure,  3. 


List    of    Weather -Bureau 

stations,  299. 
Local  attraction,  72. 

mean  time,  127. 
Locking  bands,  196. 
Logarithms,  27. 

Briggs,  27. 

common,  Table  of,  46, 

Divison  by,  38. 

Evolution  by,  42. 

Hyperbolic,  27. 

Involution  by,  40. 

Multiplication  by,  36. 

Napierian,  27. 

Natural,  27. 
Logarithm,   To   find,   of  a 

number,  30. 
Log  book,  Official,  100. 
Longitude,   Celestial,    124. 

celestial.  Circles  of,  123. 

Definition  of,  92. 

determinations,  135. 

Difference  of,  93. 
Longitudinals  244. 
Long  splice.  To  make,  272. 

ton  table,  2. 
Loxodromic  curve,  93. 
Lyddite  explosive,  218. 

M 

Machine  guns,  188. 
Machinists,  Duties  of,  162. 
Magnet,  Artificial,  68. 

Natural,  68. 
Magnetic    attraction    and 
repulsion,  69. 

axis,  69. 

coefficients,  74. 

components,  70. 

dip,  70. 

equator,  70. 

induction,  70. 

meridian,  69. 

polarity,  69. 

poles,  68. 

property   of   the    earth, 
69. 

variation,  70. 
Magnetism,  Definitions  re- 
lating to,  68. 

Retentive,  72. 


INDEX 


Magnetism,  Subperma- 

nent,  72. 
Main    engine    of    torpedo, 

228. 
Manila  rope,  261. 

rope.  Breaking  strain  of, 
266. 
Man-of-war  boats,  185. 

Organization  of,  165. 
Mantissa,  28. 

Manufacture  of  guns,  194. 
Marine,   Merchant,   of  the 

world,  311. 
Mariners,    Notice   to,    108. 
Marlinespike,  270. 
Master-at-arms,  Duties  of, 

161. 
Mates  in  the  Navy,  163. 
Maximum    separation. 

Point  of,  94. 
Mean  proportional,  17. 

solar  day,  126. 

sun,  126. 

time,  126. 
Measure,  Cubic,  1. 

Dry,  2. 

Linear,  1. 

Liquid,  3. 

of  angles,  2, 

Square,  1. 
Measures  and  weights,    1. 

foreign,  Value  of,  12. 

of  length,  9. 

of  money,  5. 

of  surface,  9. 

of  time,  3. 

of  volume,  4. 

of  volume  and  capacity, 
9. 

of  weight,  9. 
Mechanism,  Breech,  200. 
Medical  corps,  151. 
Melinite,  218. 
Memoranda,  Nautical,  304. 
Mensuration,  22. 
Mercator's    chart,    Con- 
struction of,  105. 

sailing,  94. 
Merchant  marine.  Number 
and  tonnage  of  ships 
in,  307. 


Merchant    marine    of    the 

world,  311. 
Mercurial     barometer. 
Weather      indications 
by,  281. 
Mercury,     Fulminate     of, 

217. 
Meridian  altitude  of  a  star, 
130. 
altitude    of    the    moon, 

131. 
altitude  of  the  sun,  129. 
Magnetic,  69. 
Prime,  92. 
Meridians,  Celestial,  120. 
of  the  earth,  92. 
used  on  foreign   charts, 
117 
Meridional     difference     of 
latitude,  94. 
parts,  94. 
Messmen  branch,  158. 
Metacenter,  237. 
Metacentric  height,  237. 
Meteorological  o  b  s  e  r  v  a  ■ 

tions  at  sea,  290. 
Methods  in   coast  naviga- 
tion, 109. 
of  plating  ships,  248. 
Method,  Sumner's,  142. 
Metric  equivalents,  10. 

svstem,  8. 
Middle  latitude,  93. 

latitude  sailing,  93. 
Miles,    Nautical,    to    kilo- 
meters, 11. 
Minors,    Naturalization 

laws  for,  322. 
Modification  of   treatment 
of  apparently  drowned 
persons,  319. 
Money,  English,  5. 
foreign,  Values  of,  6. 
Measures  of,  5. 
United  States,  5. 
Monitors,  179. 
Moon,  Meridian  altitude  of, 

131. 
Motion,  Diurnal,  120. 
of  hurricanes,  284. 
Mounts,  Gun,  208. 


XIV 


IXDEX 


Mounts,  Turret,  210. 
Multiplication    by    1  o g a- 
rithms,  36. 

of  decimals,  16. 

of  fractions,  13. 

N 
Names  of  lights  in  different 

languages,  118. 
Napierian  logarithms,  27. 
Naturalization    laws   for 
Chinese,  322. 
laws  for  minors,  322. 
laws,  U.S.,  320. 
Naturalized  citizens,    Pro- 
tection abroad  to,  322. 
Natural  logarithms    27. 

magnet,  68. 
Nautical      memoranda, 
304. 
miles  to  kilometers,   11. 
Naval  apprentices,  161. 
guns,  187. 

officers.  Insignia  of,  153. 
ordnance,  187. 
ordnance.  U.  S.,  Size  and 

power  of,  212. 
powers.  Sea  strength, 
Number  of  ships,  309. 
Navigable      semicircle      in 

hurricane,  286. 
Navigating   officer,    Navy, 

166. 
Navigation,  68. 

by  dead  reckoning,  94. 
Celestial,  119. 
steam.  Progress  of,  304. 
Terms  relating  to,  91. 
Terrestrial,  91. 
Navy,   additional  rewards 
for  merit,  160. 
barge,  185. 
boats.  Rigs  of,  185. 
cutters,  185. 
dingies,  185. 
Educational  facilities  in, 

164. 
Etiquette  in,  172. 
launches,  185. 
Mates  in  the,  163. 
Organization  of,  150. 


Navy,  Outline  of  duties  in. 
161. 
Pay   table   for   men   in, 

156. 
percussion  fuse,  207. 
Refrigerating    ships    in, 

165. 
routine  in  port,  169. 
Special    pay  and    privi- 
leges in,  159. 
Special  schools  in,  164. 
training  stations,  151. 
United  States,  150. 
yards,  150. 
Net  tonnage,  256. 
Neutral  zone,  69. 
Nickel  steel,  193. 
Nitroglycerine,  216. 
Notable    steamships, 

Dimensions  of,  314. 
Notice  to  mariners,  108. 
Number    and    tonnage    of 
ships   built  in   U.   S., 
308. 
and  tonnage  of  ships  in 
merchant  marine,  307. 
and  tonnage  of  ships  in 

U.  S.  Navy,  306. 
Fourth  power  of,  19. 
of   completed    warships, 

309. 
of  flags  used  in  a  hoist, 

294. 
of    line    officers,   Navy, 

152. 
of  revolutions.  To  find, 
for  certain  speed,  258. 
To  cube,  18. 
To  find  the  logarithm  of 

a,  30. 
To  find,  whose  logarithm 

is  given,  34. 
To  square,  18. 
Numerator,  13. 


Object,    Bearings   of,  and 
distance  run.  111. 
The  bearing  of,  93. 

Objects  at  sea.   Distances 
of,  114. 


INDEX 


Obliquity   of  the   ecliptic, 

120. 
Obry  gear.  229. 
Observations,   Meteorolog- 
ical, at  sea,  290. 
Observed  altitude,  121. 
Occultation,  126. 
Officer,  Executive.  165. 

Navigating,  166. 

of  the  deck,  166. 
Officers,  Commissioned, 
163. 

Division,  166. 

Engineer,  166. 

Line,  151. 

line,  Duties  of,  165. 

Petty.  156. 

Staff   151. 

Titles  of,  152. 

Warrant,  152. 

Watch,  166. 
Official  log  book.  100. 
Oil,  Use  of,  in  heavy  sea, 

303. 
One-flag  signal,  294. 
Opposition,  126. 
Ordnance,  Naval,  178. 

U.    S.    naval.    Size   and 
power  of,  212. 
Organization  of  a  man-of- 
war,  165. 

of  crew,  166. 

of  the  Nav>%  150. 
Outline    of    duties   in    the 
Navy.  161. 


Parallax  Annual,  123, 

in  altitude,  123. 
Parallelogram     and     rect- 
angle, 24. 
Parallelopiped    or    prism. 

26. 
Parallel  sailing,  93. 
Parallels     of     declination, 
122. 
of  latitude,  92. 
Parts.  Meridional.  94. 
Pav  corps,  152. 

table.  Navy,  156. 
Pelorus,  Use  of,  90. 


Percentage,  22. 

of  slip,  Rule  to  find,  258. 

To  find,  having  rate  and 
base,  22. 
Percussion  fuse,  207. 

primer.  202. 
Persons  that  are  appar- 
ently drowned.  To 
restore,  315. 
Pettv  officers,  156. 
Pilot.   Signals   for.   301. 
Piston,    Hydrostatic.   226. 
Plane  sailing,  93. 

trigonometry,  64. 
Planets,  Exterior.  124. 

Interior,  124. 
Plating.  Methods  of,  248. 
Plotting      a      great-circle 
track,  108. 

of  Sumner  lines,  143. 
Point  of  maximum  sepa- 
ration, 94. 
Points.  Equinoctial,  119. 

of    compass    in    variotis 
languages,  88. 

Solstitial,  120. 
Polar  distance,  122. 
Polarity.  Blue.  69. 

Magnetic.  69. 

Red,  69. 
Poles,  Celestial.  119. 

Magnetic,  68. 

of  the  earth.  92. 
Position,  Line  of,  142. 

of    ship    in    relation    to 
storm  track.  To  find, 
287. 
Pound  sterling,  8. 
Powder,  Black,  218. 

Brown,  219. 

chamber  of  a  gun,  197. 

Cocoa,  220. 

Cordite,  222. 

division,  167. 

Granulation  of,  222. 

Progressive,  222. 

Shimose,  218. 

Smokeless.  221. 

Various  forms  of,  224. 
Preliminary  considerations 
in  ship  building.  235. 


XVI 


INDEX 


Prime  meridian,  92, 

vertical,  121. 
Primer,  Combination,  203. 
Electric,  202. 
Percussion,  202. 
Primers,  201. 

Principal  ports,  Sailing  dis- 
tances between,  146. 
Principle  of  gas  checking, 

201. 
Principles     of     gun     con- 
struction, 189. 
of  ship  construction,  235. 
Prism,  Frustum  of,  26. 
or  parallelepiped,  26. 
Problems  on  speed,  257. 
Progressive  powder,  222. 
Progress  of  steam  naviga- 
tion, 304. 
Projectile,  Rotating  band 

of,  203. 
Projectiles,  203. 
Capped,  205. 
Promotion  of  enlisted  men, 

163. 
Propellers  of  torpedo,  228. 
Propeller,  The  slip  of,  257. 
Properties  of  steel,  192. 
Property,  Magnetic,  of  the 

earth;  69. 
Proportion,  16. 
Compound,  17. 
Simple,  16. 
Proportional,  Mean,  17. 
Protected  cruisers,  179. 
Protection  abroad  to  nat- 
uralized citizens,  322. 
of  wire  rope,  265. 


Quadrantal  deviation,  72. 
deviation.  To  compen- 
sate, 74. 

Quadrature,  126. 

Quartermasters,  Duties  of, 
162. 

Quarters,  General,  168. 

R 

Rackarock,  217. 
Radius  of  a  sphere,  91. 


Rammer,  Hydraulic,  211. 

Rapid-fire  guns,  188. 

Rate    and    base.    To    find 
percentage,  22. 

Rating    of    enlisted    men, 
155. 

Rational  horizon,  120. 

Ratline,  263. 

Reciprocal     bearings,     Si- 
multaneous, 79. 

Record,  Enlistment,  169. 

Recruiting  stations,  154. 

Rectangle    and    parallelo- 
gram, 24. 

Red  polarity,  69. 

Reduction    of    compass 

points  to  degrees,  86. 

of  compound  to   simple 

fractions,  14. 
of  fractions  to  decimals, 

14. 
of  simple  to  compound 
fractions,  14. 

Reef  knot,  277. 

Refraction,  123.  _ 

Refrigerating  ships  in  the 
Navy,  165. 

Remarks  on  compass  man- 
agement, 81. 

Repulsion  and   attraction, 
Magnetic,  69. 

Requirements    for    enlist- 
ment, 155. 

Retentive  magnetism,  72. 

Reverse  bar,  238. 

Revolutions,  To   find,  for 
certain  speed,  258. 

Rewards,     Additional,     in 
the  Navy,  160. 

Rhumb  track,  93. 

Rifled  gun,  187. 

Rifling  the  bore,  196. 

Right  ascension,  122. 
of  suffrage,  322. 

Rigs  of  Navy  boats,  185. 

Ring,  Circular,  27. 

Root,   Extraction  of  any, 
19. 

Rope,     manila.     Breaking 
strain  of,  266. 
White,  262. 


INDEX 


Rope.  Wire.  263. 

Wire,  Protection  of,  265. 

vams,  263. 
Ropes.  261. 

Coir,  262. 

Fiber.  261. 

Hemp,  261. 

How  to  belay,  281. 

Manila,  261. 

Shroud-laid,  263. 

Splicing,  270. 

Twisting,  262, 
Rotating  band,  198. 

band  of  projectile,  203. 
Routine    in    port    of    the 

Navy,  169. 
Rule  for  characteristic,  29. 

for    finding    number    of 
horsepower,  254. 

of  three.  Double,  17. 

of  three.  Single,  16. 
Rules  for  action  to  avoid 

storm  center,  288. 
Running   gear,    wire    rope 
for,  Strength  of,  269. 


Sailing,  Composite,  94. 

distances  between  prin- 
cipal ports,  146. 

Great-circle,  94. 

Mercator's,  94. 

Middle-latitude,  93. 

Parallel,  93. 

Plane,  93. 

Traverse,  94. 
Schools.    Special,    in    the 

Navy,  164. 
Screw  box  of  a  gun,  197. 
Sea  horizon,  121. 

strength  of  Naval  pow- 
ers, 309. 

Use  of  on  in  heavy,  303. 
Seamen  branch,  156. 

How  to  become  citizens, 
321. 
Secant  of  an  angle,  65. 
Sector,  25. 
Segment,  25. 
Selected     International 

Code  signals,  294. 


Semiautomatic  guns,   189. 
Semicircle,  Dangerous,  284 

Navigable,  286. 
Semicircular  deviation,  72. 
Sensible  horizon,  120. 
Separation,  maximum. 

Point  of,  94. 
Sheepshank,  277. 
Sheet  bend,  277. 
Shells,     Armor-piercing 
204. 
Common,  204. 
Shimose  powder,  218. 
Shipboard,   Division  of 

time,  171. 
Ship  building,  235. 

Displacement  of  a.  254. 
position  of.  To  find,  in 
relation   to   storm 
track,  287. 
To  swing,  for  deviation, 
79. 
Ships,  Battle,  174. 

Handling,  in  hurricanes, 

286. 
in      merchant      marine. 
Number  and  tonnage 
of,  307. 
Number  and  tonnage  of, 

in  U.  S.  Navy,  306. 
Strain  in.  238. 
war.     Classification     of, 
173. 
Ship's  writer,  169. 
Short  splice.  To  make,  271. 
Shrapnel,  205. 
Shroud-laid  ropes,  263. 
Side-bar  keel,  240. 

keelson,  240. 
Sidereal  day,  127. 

time,  127. 
Sights,    Sunrise    and   sun- 
set   139 
Signal,  One-flag,  294. 
Signals,  Distant,  296. 
distant.  Special,  296. 
for  pilot,  301. 
Four-flag,  294. 
Hurricane  warning,  301. 
International     Code    of, 
293. 


INDEX 


Signals,  Life-saving,  302. 

of  distress,  300. 

Storm,  301. 

Three-flag,  294, 

Two-flag,  294. 
Simple    fractions,    Reduc- 
tion to  compound,  14. 

proportion,  16. 
Simultaneous        reciprocal 

bearings,  79. 
Sine  of  an  angle,  64. 
Single  rule  of  three,  16. 
Sinking   gear   of    torpedo, 

231. 
Size   and  power  of  U.  S. 

naval  ordnance,  212. 
Slip  of  the  propeller,  257. 

percentage   of.    Rule   to 
find,  258. 
Slope,  Band,  198. 

Chamber,  198. 

Gas-check,  198. 
Small  circle,  92, 

stuff,  263. 
Smokeless  powder,  221. 
Soft  iron,  72. 
Solar  day.  Apparent,  126. 

system,  124. 
Solstitial  points,  120. 
Soundings    on    foreign 

charts,  118. 
Sound,  To  find  distance  by, 

115. 
Special  branch,  158. 

distant  signals,  296. 

pav  and  privileges  in  the 
Navy,  159. 

schools  in  the  Navy,  164. 
Speed  and  fuel  consump- 
tion, 259. 

of  vessels.  Notes  on,  253. 

Problems  on,  257. 
Sphere,  26. 

Celestial,  119. 

Diameter  of,  91. 

Radius  of,  91. 
Spherical  angle,  92, 

triangle,  92. 
Splice,    chain.    To    make, 
274. 

eye.  To  make,  274. 


Splice,  long.  To  make,  272. 

short.  To  make,  271. 
Splices  and  bends,  270. ' 
Splicing  in  wire,  275. 
of  ropes,  270. 
wire,  lools  for,  276. 
Spun  yam,  263. 
Squadron,    Definition    of, 

184. 
Square  measure,  1. 
Stability,  236. 
Staff  corps,  151. 

officers,  151. 
Star  gauging,  196. 

Meridian  altitude  of,  130. 
Time  sight  of,  137. 
Station  billet,  169. 
Stations,  Recruiting,  154. 
Weather-Bureau,  List  of, 
299. 
Steam  launches,  185. 
navigation.  Progress  of, 
304. 
Steamship  companies,  lar- 
gest. Table  of,  312. 
Steamships,    notable.    Di- 
mensions of,  314. 
Steel,  Composition  of,  192, 
Elastic  strength  of,  192, 
gun,  191. 

hawsers  for  heavv  tow- 
ing. Strength  of,  268. 
Nickel,  193. 
Properties  of,  192. 
Tensile  strength  of,  192. 
Steering  of  torpedoes,  228. 
Sterling,  Pound,  8. 
Storm   center.   Actions  to 
avoid,  288. 
center,    approaching    or 
receding.  To  find,  288. 
center.    Description    of, 

289. 
signals,  U.  S.,  301. 
track,   To  find  position 
of  ship  in  relation  to, 
287. 
warning  flags,  30 1. 
Strain  in  ships,  238. 
Strength  of  cast-steel  wire 
rope,  269. 


INDEX 


Strength,     of    galvanized- 
steel  hawsers,  268. 
of     steel     hawsers     for 

heavy  towing,  268. 
of  wire  rope  for  running 
gear,  269. 
Stringers,  240. 
Stringer,  The  deck,  241. 
Stuff,  Small,  263. 
Subpermanent  magnetism, 

72. 
Subtraction    of    decimals, 
15. 
of  fractions,  13. 
Suffrage,  Right  of,  322. 
Sumner  line,  142. 

lines,  Plotting  of,  143. 
Sumner's  method,  142. 
Sun,  Ex-meridian  of,  133. 
Mean,  126, 
Meridian     altitude      of, 

129. 
Time  sight  of,  135. 
Sunrise  and  sunset  sights, 

139. 
Superior  conjunction,  124. 
Supplement  of  an  arc,  64. 
Surface,  Measures  of,  9. 
Swinging  a  ship  for  devia- 
tion, 79. 
System,  Metric,  8. 
Solar.  124. 


Table,  Long-ton,  2. 

of  common  logarithms, 
46. 

of  compass  points,  86. 

of  constants,  255. 

of  distances,  4. 
Table  of  distances  of  vis- 
ibility at  sea,  114. 

of  elements  in  solar  sys- 
tem, 125. 

of  foreign  money,  6. 

of   completed  warships, 
310. 

of  fractions,  15. 

of    largest    steamship 
companies,  312. 

of  latitudes,  104. 


Table  of  merchant  fleet  of 

the  world,  311. 

of  metric  equivalents,  10. 

of  naval  ordnance.  212. 

of    notable    merchant 

steamships,  314. 
of  sailing  distances,  146. 
of  vessels  built  in  U.  S., 

308. 
Pay,  of  the  Navy,  156. 
Tables    for    two    bearings 
and  distance  run,  112. 
Traverse,  94. 
Tangent  of  an  angle,  64. 
Tensile    strength    of   steel, 

192. 
Terms,  Astronomical,  119. 
relating    to    navigation, 
91. 
Terrestrial  navigation,  91. 
Three-flag  signals,  294. 
Time,  Division  of,  on  ship- 
board, 171. 
Equation  of,  126. 
fuse,  206. 
Local  mean,  127. 
Mean,  126. 
Measures  of,  3. 
Sidereal,  127. 
sight  of  a  star,  137. 
sight  of  the  sun,  135. 
Titles  of  officers,  152. 
To  cube  a  number,  18. 
find  approaching  or  rece- 
ding storm  center,  288. 
find  center  of  hurricane, 

287. 
find  logarithm  of  a  num- 
ber, 30. 
find  number  whose  loga- 
rithm is  given,  34. 
produce  breathing,  316. 
restore    persons    appar- 
ently drowned,  315. 
square  a  number,  18. 
Tonnage    and    displace- 
ment, 256. 
and     number     of     ships 

built  in  U.  S.,  308. 
and  number  of  ships  in 
U.  S.  Navy,  306. 


INDEX 


Tonnage,  Gross,  256. 

Net,  256. 

of   completed  warships, 
310. 
Tools  for  splicing  in  wire, 

276. 
Top  carriage  of  a  gun,  209. 
Torpedo,  Air  flask  of.  225. 

boat  destroyers,  184. 

boats,  179. 

boats,     Importance     of, 
234. 

director,  232. 

Exercise  head  of,  225. 

Main  engine  of,  228. 

Propellers  of,  228. 

Sinking  gear  of,  231. 

War  head  of,  225. 

Whitehead,  224. 
Torpedoes,  224. 

Launching  tubes  of,  231. 

Steering  of,  228. 
Track,      great-circle,      To 
plot,  108. 

The  rhumb,  93. 
Training  stations,  151. 
Transit  or  transition,  123. 
Trapezium,  25. 
Trapezoid.  24. 
Traverse  tables,  94. 

sailing,  94. 
Treatment,  M  o  d  i  f  i  e  d,  of 
apparently      drowned 
persons,  319. 

of  gun  steel,  193. 
Triangle,  Spherical,  92. 
Triangles,  23. 
Trigonometric      functions, 

65. 
Trigonometry    applied    in 
practice,  66. 

Plane,  64. 
Trov  weight.  2. 
True  altitude.  121. 

amplitude,  122. 

azimuth,  121. 

course,  83. 

course.  To  find  compass 
course  from,  84. 

horizon,  120. 
Turret  mounts,  210. 


Twisting  of  ropes.  262. 
Two  bearings  and  distance 
run.    Tables    oi    con- 
stants for,  112. 
flag  signals,  294. 
Types  of  keel,  241. 
of  wire  rope.  264. 
Typhoons,  Indications  of, 
289. 

U 

United  States  money,  5. 

naturalization  laws.  320. 

naval  ordnance.  Size  and 
power  of,  212. 

Navy,  150. 

Navy,  Number  and  ton- 
nage of  ships  in,  306. 

storm  signals,  301. 
Use   of  oil  in  heavy   sea, 
303. 

of  pelorus,  90. 


Value  of  foreign  measures, 
12. 
of  foreign  money,  6. 
Variation,  Magnetic,  70. 
Velocity  of  sound.  To  find 

distance  by,  115. 
Vent-sealing,  202. 
Vernal  equinox,  119. 
Vertex  of  a  great  circle,  94. 
Vertical     and     horizontal 
iron,  72. 
danger  angle,  116. 
Prime,  121. 
Verticals,  121. 
Vessels    built    in     United 
States,    Number    and 
tonnage  of,  308. 
speed  of.  Notes  on,  253. 
Volume  [and    capacity, 
Measures  of,  9, 
Measures  of,  4. 

W 

War  head  of  torpedo,  225. 
ships,    Classification    of, 
173. 


INDEX 


xxi 


Warships,     completed. 
Number  of,  309. 
ships,    completed.    Ton- 
nage of,  310. 
Warrant  officers,  152. 
Watch  officers,  166. 

quarter    and    station 
book. 169. 
W  a  t  e  r-tight       compart- 
ments, 245. 
Weather  and  wind,  281. 
Bureau  stations,  List  of, 

299. 
indications    by    aneroid 

barometer,  283. 
indications    by    appear- 
ance of  sky,  283. 
indications  by  mercurial 

barometer,  281, 
observance,  291. 
'Wedge,  27. 

Weight,  Avoirdupois,  2. 
Measures  of,  9. 
Troy,  2. 
'Weights  and  measures,  1. 
'Welin  breech  lock,  199. 
'Whale  boats,  185. 
^Whitehead  torpedo,  224. 


White  rope,  262. 

Wind  and  weather,  281. 

Wire  rope,  263. 

rope,  cast-steel.  Strength 

of,  269. 
rope    for   running   gear, 

Strength  of,  269.  _ 
rope,    galvanized-iron. 
Breaking     strain     of, 
267. 
rope.  Protection  of,  265. 
rope.  Types  of,  264. 
Splicing  of,  275. 
splicing.  Tools  for,  276. 
Work,  The  dav's,  100. 
Writer,  Ship's,  169. 


Yards,  Navy,  150. 
Yam,  Spun,  263. 
Yams,  Rope,  263. 
Yeomen,  158. 
Duties  of,  163. 


Zenith,  120. 

distance, 121. 
Zone,  Neutral,  € 


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MARINERS'  Handbook 


USEFUL   TABLES 


WEIGHTS  AND  MEASURES 

LINEAR  MEASURE 

12    inches  (in.) =1  foot ft. 

3    feet =  1  yard yd. 

5i  yards =  1  rod rd. 

40    rods =  1  furlong fur. 

8    furlongs =1  mile mi. 

in.  ft.  yd.         rd.  fur.  mi. 

36  =         3  =         1 
198=    16.5=      5.5=      1 
7,920=     660=     220=   40  =  1 
63,360  =  5,280  =  1,760  =  320  =  8  =  1 

SQUARE  MEASURE 

144     square  inches  (sq.  in.) .  .   =  1  square  foot sq.  ft. 

9    square  feet =  1  square  yard sq.  yd. 

30  J  square  yards =  1  square  rod sq.  rd. 

160    square  rods =  1  acre A. 

640    acres =1  square  mile sq.  mi. 

sq.mi.A.       sq.  rd.         sq.  yd.  sq.  ft.  sq.  in. 

1  =  640  =  102,400  =  3,097,600  =  27,878,400  =  4,014,489.600 

CUBIC  MEASURE 

1,728  cubic  inches  (cu.  in.)  .  .   =  1  cubic  foot cu.  ft. 

27  cubic  feet =  1  cubic  yard cu.  yd. 

128  cubic  feet =  1  cord cd. 

24|  cubic  feet =  1  perch P. 

1  cu.  yd.  =27  cu.  ft.  =46,656  cu.  in. 


2  USEFUL  TABLES 

MEASURE  OF  ANGLES  OR  ARCS 

60  seconds  (") =  1  minute . . .' 

60  minutes =  1  degree • 

90  degrees =  1  rt.  angle  or  quadrant.  . Q 

360  degrees =  1  circle ci  •. 

1  cir.=360°  =  21,600'  =  l,296,000'' 

A  quadrant  is  one-fourth  the  circumference  of  a  circle,  or 
90°;  a  sextant  is  one-sixth  of  a  circle,  or  60°.  A  right  angle 
contains  90°.  The  unit  of  measurement  is  the  degree  or 
j^  of  the  circumference  of  a  circle. 

AVOIRDUPOIS  WEIGHT 

437^  grains  (gr.) =  1  ounce oz. 

16    ounces =1  pound lb. 

100    pounds =1  hundredweight cwt. 

20    cwt.,  or  2,000  lb =1  ton T. 

1  T.  =  20  cwt.  =2,000  lb.  =  32,000  oz.  =  14,000,000  gr. 
The  avoirdupois  pound  contains  7,000  gr. 

LONG-TON  TABLE 

16  ounces =  1  pound lb. 

112  pounds =  1  hundredweight cwt. 

20  cwt.,  or  2,240  lb =  1  ton T. 

TROY  WEIGHT 

24  grains  (gr.) =  1  pennyweight pwt. 

20  pennyweights =  1  ounce oz. 

12  otmces =  1  pound lb. 

1  lb.  =  12  oz.  =  240  pwt.  =  5,760  gr. 

DRY  MEASURE 

2  pints  (pt.) =1  quart qt. 

8  quarts =  1  peck pk. 

4  pecks =1  bushel bu. 

1  bu.  =  4  pk.=32  qt.  =  64  pt. 

The  U.  S.  struck  bushel  contains  2,150.42  cu.  in.  =  1.2444 
cu.  ft.  By  law,  its  dimensions  are  those  of  a  cylinder  18J 
in.  in  diameter  and  8  in.  deep.  The  heaped  bushel  is  equal 
to  li  struck  bushels,  the  cone  being  6  in.  high.  The  dry 
gallon  contains  268.8  cu.  in.,  being  \  struck  bushel. 


USEFUL  TABLES 


For  approximations,  the  bushel  may  be  taken  as  1 J  cu.  ft.; 
or  1  cu.  ft.  may  be  considered  f  bu. 

The  British  bushel  contains  2,218.19  cu.  in.  =  1.2837  cu.  ft. 
=  1.032  U.  S.  bushels. 

LIQUID  MEASURE 


4    gills  (gi.) 

2    pints 

4     quarts 

31i  gallons 

2    barrels,  or  63  gallons 


=  1  pint pt. 

=  1  quart qt. 

=  1  gallon gal. 

=  1  barrel bbl. 

=  1  hogshead hhd. 


1  hhd.=2  bbl.  =  63  gal.=252  qt.=504  pt.=2,016  gi. 

The  U.  S.  gallon  contains  231  cu.  in.  =  .134  cu.  ft.,  nearly, 
or  1  cu.  ft.  contains  7.481  gal.  The  following  cylinders  con- 
tain the  given  measures  very  closely; 


Gill... 
Pint.. 
Quart. 


Diam.  Height 
..IJ  in.  3  in. 
.  .3^  in.  3  in. 
.  .3i  in.     6  in. 


Diam.  Height 

Gallon 7  in.  6  in. 

8  gallons.  ..14  in.  12  in. 

10  gallons. .  .14  in.  15  in. 


When  water  is  at  its  maximum  density,  1  cu.  ft.  weighs 
62.425  lb.  and  1  gal.  weighs  8.345  lb. 

For  approximations,  1  cu.  ft.  of  water  is  considered  equal 
to  7i  gal.,  and  1  gal.  as  weighing  8i  lb. 

The  British  imperial  gallon,  both  liquid  and  dry,  con- 
tains 277.274  cu.  in.  =  .16046  cu.  ft.,  and  is  equivalent  to 
the  volume  of  10  lb.  of  pure  water  at  62°  F.  To  reduce 
British  to  U.  S.  liquid  gallons,  multiply  by  1.2.  Conversely, 
to  convert  U.  S.  into  British  liquid  gallons,  divide  by  1.2; 
or,  increase  the  number  of  gallons  \. 


MEASURES  OF  TIME 


60  seconds  (sec). 

60  minutes 

24  hours 

7  days 

4  weeks 

12  month 

100  years 


=  1  minute min. 

=  1  hour hr. 

=  1  day da. 

=  1  week wk. 

=  1  month mo. 

=  1  year yr. 

=  1  century C. 


4  USEFUL  TABLES 

sec.  min.         hr.       da.   wk.  yr. 

60=  1 

3,600=  60=         1 

86,400=      1,440=       24=      1 
604,800=    10,080=     168=      7=    1 
31.556,936  =  525,948  =  8,765  =  365  =  52  =  1 

TABLE  OF  DISTANCES 

1  statute  or  land  mile =  5,280  ft.;  1,760  yd.; 

320  rd.;  8  fur. 

1  furlong =  40  rd. 

1  league =3  mi. 

1  knot,*  or  nautical  mile =  6,080  ft.,  or  IJ  mi. 

1  nautical  league =3  naut.  mi. 

1  fathom =  6  ft. 

1  meter =3  ft.  3f  in.,  nearly 

1  hand =  4  in. 

1  palm =  3  in. 

1  span =  9  in. 

1  cable's  length =  240  yd. 

Austrian  mile =  4.09  naut.  mi. 

Danish  mile =  4.06  naut.  mi. 

French  kilometre =     .54  naut.  mi. 

German  Ruthen =  4.06  naut.  mi. 

Italian  mile =  1.00  naut.  mi. 

Norwegian  mile =  6.01  naut.  mi. 

Russian  verst =     .57  naut.  mi. 

Swedish  mile =  5.75  naut.  mi. 

MEASURES  OF  VOLUME 

1  cubic  foot =  1 ,728  cu.  in. 

1  ale  gallon =  282  cu.  in. 

1  standard,  or  wine,  gallon =  231  cu.  in. 

1  dry  gallon =  268.8  cu.  in. 

1  bushel =  2,150.4  cu.  in 

1  British  bushel =  2,218.19  cu.  in. 

1  cord  of  wood =  128  cu.  ft. 

•A  knot  is  really  a  measure  of  speed  and  not  of  distance;  when  used  in  this 
sense,  it  is  eijuivalent  to  1  naut.  mi.  in  1  hr.  Thus,  a  vessel  running  20  naut. 
mi.  per  hr.  has  a  speed  oi  20  Icnots. 


USEFUL  TABLES 

1  perch =  24.75  cu.  ft. 

1  ton  of  round  timber =40  cu.  ft. 

1  ton  of  hewn  timber =50  cu.  ft. 

A  box  12^1  in.  long,  wide,  and  deep  contains  1  bu. 

A  box  19f   in.  long,  wide,  and  deep  contains  1  bbl. 

A  box    8|  in.  long,  wide,  and  deep  contains  1  pk. 

A  box    6/5  in.  long,  wide,  and  deep  contains  i  pk. 

A  box    4i')|  in.  long,  wide,  and  deep  contains  1  qt. 


MEASURES  OF  MONEY 


UNITED  STATES  MONEY 

=  1  cent ct. 

=  1  dime d. 

=  1  dollar I 

=1  eagle E. 

d.      $     E. 


10  mills  (m) = 

10  cents = 

10  dimes = 

10  dollars = 

m.  ct. 

10=         1 

100=       10=     1 
1.000=     100=    10=    1 
10,000  =  1,000  =  100  =  10  =  1 
The  term  legal  tender  is  applied  to  money  that  may  be 
legally  offered   in    payment   of    debts.     All   gold   coins   are 
legal  tender  for  their  face  value  to  any  amount,  provided 
that  their  weight  has  not  diminished  more  than  ^J^.     Silver 
dollars   are   also   legal    tender   to   any   amount;    but   silver 
coins  of  lower  denomination  than  $1  are  legal  tender  only 
for  sums  not  exceeding  SIO.     Nickel  and  copper  coins  are 
legal  tender  for  sums  not  exceeding  25  ct. 


ENGLISH  MONEY 


4  farthings  (far.) . 

12  pence 

20  shillings 


far. 
4  = 
48  = 


.   =  1  penny d. 

.   =  1  shilling s. 

.  =  1  pound,  or 

sovereign £ 

d.       s.     £ 


12=    1 
240  =  20  =  1 


USEFUL  TABLES 


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8  USEFUL  TABLES 

The  unit  of  English  money  is  the  pound  sterling,  the 
vakie  of  which  in  United  States  money  is  $4.8665.  The 
fineness  of  English  silver  is  .925;  of  the  gold  coins,  .916f. 
What  is  called  sterling  silver  when  applied  to  solid  silver 
articles  has  the  same  fineness.  Hence  the  name  sterling 
silver. 

The  other  coins  of  Great  Britain  are  the  florin  (  =  2  shil- 
lings), the  crown  (  =  5  shillings),  the  half  crown  (  =  2^ 
shillings),  and  the  guinea  (=21  shillings).  The  largest 
silver  coin  is  the  crown,  and  the  smallest,  the  threepence 
(i  shilling).  The  shilling  is  worth  25  ct.  (24.3 +  ct.)  in 
United  States  money.  The  guinea  is  no  longer  coined.  The 
abbreviation  £  is  written  before  the  number,  while  s.  and  d. 
follow.     Thus,  £25  4s.  6d.  =  25  pounds  4  shillings  6  pence. 

Rule. — To  reduce  pounds,  shillings,  and  pence  to  dollars 
and  cents,  reduce  the  pounds  to  shillings,  add  the  shillings,  if 
any,  and  multiply  the  sum  by  .24^;  if  any  pence  are  given, 
increase  this  product  by  twice  as  many  cents  as  there  are  pence. 

Example. — Reduce  £4  7s.  14d.  to  dollars  and  cents. 

Solution.— {4  X  20  +  7)  X  .24  J  +  .28  =  $21 .45.     Ans. 

Rule. — To  reduce  pounds  to  dollars,  and  vice  versa,  exchange 
being  at  $4.8665:  Multiply  the  number  of  pounds  by  73, 
and  divide  the  quotient  fey  15;  the  result  will  be  the  equivalent 
VI  dollars  and  cents.  Or,  multiplying  the  dollars  by  \b  and 
dividing  the  product  by  73  will  give  its  equivalent  in  pounds 
and  decimals  of  a  pound. 

Example. — Reduce  £6  to   dollars  and  cents. 

Solution. —        6  X  73  H- 15  =  $29.20.     Ans. 

Example. — Reduce  $17  to  pounds. 

Solution.—       17X15 -^73  =  £3.493.     Ans. 

THE  METRIC  SYSTEM 
The  metric  system  is  based  on  the  meter,  which,  according 
to  the  United  States  Coast  and  Geodetic  Survey  Report  of 
1884,  is  equal  to  39.370432  in.  The  value  commonly  used  is 
39.37  in.,  and  is  authorized  by  the  United  States  government. 
The  meter  is  defined  as  one  ten-millionth  the  distance  from 
the  pole  to  the  equator,  measured  on  a  meridian  passing  near 
i-aris,  France. 


USEFUL  TABLES  9 

There  are  three  principal  units — the  meter,  the  liter  (pro- 
nounced lee-ter),  and  the  gram,  the  units  of  length,  capacity, 
and  weight,  respectively.  Multiples  of  these  units  are 
obtained  by  prefixing  to  the  names  of  the  principal  units 
the  Greek  words  deca  (10),  hecto  (100),  and  kilo  (1,000); 
the  submultiples,  or  divisions,  are  obtained  by  prefixing 
the  Latin  words  deci  (^),  centi  (t^tj),  and  milli  (ttjW)-  These 
prefixes  form  the  key  to  the  entire  system. 


MEASURES  OF  LENGTH 

10  millimeters  . , 

=  1  centimeter 

= 

.394    in. 

10  centimeters., 

=  1  decimeter 

= 

3.937    in. 

10  decimeters. . 

=  1  meter 

= 

3.281     ft. 

10  meters 

=  1  decameter 

32.809    ft. 

10  decameters  . , 

=  1  hectometer 

= 

109.363  yd. 

10  hectometers =  1  kilometer =     1,093.63  yd. 

MEASURES  OF  SURFACE  (NOT  LAND) 

100  sq.  millimeters  .  .  =  1  sq.  centimeter. .  ==  .155  sq.  in. 
100  sq.  centimeters...  =  1  sq.  decimeter...  =  15.5  sq.  in. 
100  sq.  decimeters.  .  .  =  1  sq.  meter =  10.764  sq.  ft. 

MEASURES  OF  VOLUME  AND  CAPACITY 

10  milliliters =1  centiliter =       .61 

10  centiliters =  1  deciliter =     6.10 

10  deciliters =  1  liter =61.02 

10  liters =  1  decaliter =     .353 

10  decaliters =  1  hectoliter =     3.53 

10  hectoliters =  1  kiloliter =  35.31     cu.  ft. 

The  liter  is  equal  to  the  volume  occupied  by  1  cu.  decimeter. 

MEASURES  OF  WEIGHT 

10  milligrams =  1  centigram  . .  .  =  .154  gr. 

10  centigrams =  1  decigram    ...  =  1.54  gr. 

10  decigrams =  1  gram =  15.43  gr. 

10  grams =  1  decagram. .  .  .  =  154.32  gr, 

10  decagrams =  1  hectogram  .  . .  =  .220  lb.,  avoir. 

10  hectograms =  1  kilogram =  2.204  lb.,  avoir. 

1,000  kilograms =  1  ton =  2.204  lb.,  avoir. 


cu. 

in. 

cu. 

m. 

cu. 

m. 

cu. 

ft. 

cu. 

ft. 

10 


USEFUL  TABLES 


The  gram  is  the  weight  of  1  cu.  cm.  of  pure  distilled 
water  at  a  temperature  of  39.2°  F.;  the  kilogram  is  the 
weight  of  1  liter  of  water;  the  ton  is  the  weight  of  1  cu.  m. 
of  water. 

METRIC  EQUIVALENTS  OF  POUNDS,  FEET,  ETC. 

The  following  table  will  be  found  valuable  for  reference 
by  masters,  officers,  and  stewards  in  their  dealings  with 
ship  chandleries  and  other  supply  stores  in  countries  where 
the  metric  system  is  used: 


Pounds 
1 

Kilos. 
=        .454 
=        .909 
=     1.363 
=     1.818 
=     2.272 
=     2.727 
=     3.161 
=     3.636 
=     4.090 
=     4.545 
=     9.060 
=  13.635 
=  18.180 
=  22.725 
.  =  1  metric  1 

Centi- 
meters 
=       2.54 
=     30.48 
=     91.44 
=     61.00 
=     91.44 
=  122.00 
=  152.00 
=  182.88 

Pounds 

60 

70 

80 

Kilos. 
=.     27 .  270 

2 

3 

..  .  =     31.815 
...  =     36.360 

4 

5 

6 

7 

8 

9 

90 

100 

200 

300 

400 

500 

600 

700 

800 

900 

1,000 

on  (Tonelada 

7  feet 

8  feet 

...  =     40.905 
.  ...  =     45.450 

...  =     90.900 
. ...  =  136.350 

...  =  181.800 
=  227.250 

10 

20 

.  ...  =  272.700 
..  .   =  318.150 

30 

40 

50 

1.000  kilos 

...   =  363.600 
..  .  =  409.050 

=  454.500 

metrico). 

Centi- 
meters 
=  213.00 

1  foot 

=  243 . 84 

1  vard 

9  feet 

=274.32 

2  feet 

10  feet 

=  304.80 

3  feet 

11  feet 

=  335.28 

4  feet     . . 

12  feet 

=  365.76 

5  feet     . . . 

13  feet 

=  396.24 

6  feet 

14  feet 

=  426.72 

USEFUL  TABLES 


11 


1  gill =  .142  liter 

1  pint =  .568  liter 

1  quart =       1 .  136  liters 

1  gallon =       4.543  liters 

1  peck =       9 .  087  liters 

1  bushel =     36.347  liters 

1  quarter =  290 .  781  liters 

1  ounce,  avoir =  2.83  decigrams 

1  pound,  avoir =  .45  kilogram 

1  hundredweight,  avoir =         50.80  kilograms 

1  ton.  avoir =  1 ,016.05  kilograms 

1  pennyweight,  troy =       1 .55  grams 

1  ounce,  troy =     31.10  grams 

1  pound,  troy =  373.24  grams 

NAUTICAL  MILES  TO  KILOMETERS 


Nautical 
Miles 

Kilometers 

Nautical 
Miles 

Kilometers 

1 

1.8532 

20 

37.064 

2 

3 . 7064 

30 

55.596 

3 

5.5596 

40 

74.128 

4 

7.4128 

50 

92.660 

5 

9.2660 

60 

111.190 

6 

ll.li90 

70 

129.720 

7 

12.9720 

80 

148.250 

8 

14.8250 

90 

167.880 

9 

16.7880 

100 

185.320 

10 

18.5320 

110 

203.850 

KILOMETERS  TO  NAUTICAL  MILES 


Kilo- 

Nautical 

Kilo- 

Nautical 

meters 

Miles 

meters 

Miles 

1 

.5396 

20 

10.792 

2 

1.0792 

30 

16.188 

3 

1.6188 

40 

21.584 

4 

2 . 1584 

50 

26.980 

5 

2.6980 

60 

32.375 

6 

3.2375 

70 

37.771 

7 

3.7771 

80 

43.167 

8 

4.3167 

90 

48.563 

9 

4.8563 

100 

53.959 

10 

5.3959 

110 

59.355 

12  USEFUL  TABLES 

VALUE  OF  MISCELLANEOUS  FOREIGN   MEASURES 

The  following  list  contains  the  value  of  various  foreign 
measures  as  given  in  Monthly  Consular  Reports  published 
by  the  Department  of  Commerce  and  Labor.  Many  of 
the  equivalents  are  probably  only  approximately  correct. 
Argentine   Republic. — 1    frasco  =  2.5    qt.,    1  baril  =  20.1    gal., 

1  libra  =  1  lb..  1  vara  =  34.1  in.,  1  arroba  (dry)  =25.3  lb. 

1  quintal  =  101.4  lb. 
Belgium. — 1  last  =  85.1  bu. 

Brazil— I  arroba  =  32.4  lb.,  1  quintal  =  130  lb. 
Chile.— I  fanega'(dry)=2.5  bu.,  1  vara  =  33.3  in. 
China.— I  catty  =  1.3  lb..  1  picul  =  133.3  lb.,  1  chik  =  14in., 

1  tsun  =  1.4  in.,   1  li  =  2,115  ft. 
Costa  Rico. — 1  manzana  =  1.8  A. 
Cuba. — 1  vara  =  33.4  in.,  1  arroba  (liquid)  =  4.3  gal..  1  fanega 

(dry)  =  1.6  bu.,  1  libra  =  1  lb. 
Denmark. — 1  tonde  (cereals)   =3.9  bu..  1  centner  =  110.1  lb. 
Greece.—!  livre  =  l.l  lb.,  1  oke  =  2.8  lb..  1  quintal  =  123.2  lb. 
Japan. — 1    sun  =  1.2   in.,    1    shaku  =  11.9   in.,    1    ken  =  6   ft., 

1   sho  =  1.6    qt.,  1    to  =  2  pk.,  1   koku  =  4.9    bu.,  1  catty 

=  1.31b.,  1  picul  =  133.3  lb. 
Mexico. — 1   carga  =  300  lb.;  other  measures  same  as  Cuba 

and  Argentine  Republic. 
Peru.— I  vara  =  33.4  in.,  1  libra  =  1  lb..  1  quintal  =  101.4  lb. 
Portugal. — 1   almuda  =  4.4  gal..    1   arratel  =  l    lb.,    1    arroba 

=  32.4  lb. 
Russia. — 1   vedro  =  2.7  gal.,   1   korree  =  3.5  bu.,    1    chetvert 

=  5.7  bu.,  1  funt  =  .9  lb.,  1  pood  =  36.1  lb.,  1  berkovets 

=  361.1  lb.,  1  verst  =  0.66  mi. 
Siam. — 1  catty  =  1.3  lb.,  1  coyan  =  2,667  lb. 
Spain. — 1  pie  =  .9  ft.,  1  vara  =  .9  yd.,  1  arroba(liquid)  =  4.3  gal. 

1    fanega    (liquid)  =  16    gal.,  1  butt  (wine)  =  140  gal.,  1 

last  (salt)  =4.760  lb. 
Sweden. — 1   tunna  =  4.5  bu.,  1   sk^lpund  =  l.l  lb.,  1  centner 

=  93.7  lb. 
Turkey.— I  pik  =  27.9  in.,  1  oke  =  2.8  1b..  1  cantar  =  124.7  lb. 
Uruguay. — 1     cuadra=  2    A.,    1   suerte  =  2,700    cuadras,    1 

fanega  (single)  =3.8  bu.,   1  fanega  (double)  =    7  7  bu. 
Zanzibar. — 1  frasila  =  35  lb. 


ARITHMETIC  13 

ARITHMETIC 
COMMON  FRACTIONS 

Two  numbers  are  required  to  express  a  fraction;  one 
is  called  the  numerator  and  the  other  the  denominator. 
The  numerator  is  the  number  that  tells  how  many  parts 
of  a  whole  is  taken.  Thus,  2  is  the  numerator  of  |,  as  it 
shows  that  two  of  three  parts  into  which  the  whole  is  divided 
are  taken.  The  denominator  of  a  fraction  is  the  number 
that  shows  into  how  many  parts  the  whole  is  divided.  Thus, 
in  the  fraction  ^  the  3  is  the  denominator.  A  common 
denominator  is  a  denominator  that  is  common  to  two  or 
more  fractions.  Thus,  \  and  f  have  common  denominators; 
and  12  is  a  common  denominator  for  \,  ^,  \,  and  ^  as  they 
are,  respectively,  equal  to  -fn,  /i,  f^,  and  i%. 

Addition  of  Fractions. — If  of  the  same  denominator,  add 
together  the  numerators  only.     Thus,  TB  +  TB  +  TB  =  fB- 

If  they  have  different  denominators,  change  them  to 
fractions  with  common  denominators  and  then  proceed 
as  before. 

Example. — What  is  the   sum  of   a  +  i  +  s? 

Solution. — We  have    3  =  IS,    4  =  M.   and  5  =  i§;  hence, 
«8  +  M  +  bS  =  ss-     Ans. 

Subtraction    of   Fractions. — Reduce    them    to    a    common 

denominator,   take   the   less  from   the  greater,   and  reduce 

4.V  1.  7  .  9    .  14-9        5   .         ^,  ^. 

the  result;  as,  —  m.  —  -7.  m.  =  — -~ —  =  — ;  m.     It  they  are 
o  lb  lb  lb 

mixed  numbers,  subtract  fractie.ns  and  whole  numbers  sepa- 
rately, placing  remainders  besic..3  one  another;  thus,  3|  in. 
-2Hn.  =  (3-2)  +  (t-|)  =  lf  in. 
Multiplication  of  Fractions. — Multiply  the  numerators 
■together  for  the  numerator  and  the  denominators  for  the 
denominator.     Thus, 

1^       _3        2  _        2X3        _  1  _  J__ 
2       16       3       2  X  16  X  3       96       16 
Division  of  Fractions. — Invert  the  divisor  and  multiply. 
Example. — Divide  b\  by  f. 
Solution. —  ^Xf  =  i*2s-     Ans. 


14  ARITHMETIC 

Reduction  of  Compound  to  Simple  Fractions. — Mvdtiply 
the  integer  by  the  denominator  of  the  fraction  and  add 
the  numerator  for  the  new  numerator  and  place  it  over 
the  denominator. 

Example. — Reduce  5§  to  a  simple  fraction. 

Solution. —  5X3  +  2  =  17,  which  is  the  numerator,  and 
the  fraction  is  therefore  -\f.     Ans. 

Reduction  of  Simple  to  Compound  Fractions. — Divide  the 
numerator  by  the  denominator  and  use  the  remainder  as 
the  numerator  of  the  remaining  fraction. 

Example. — Reduce  -%*  to  a  compound  fraction. 

Solution. —  9)64(7 

63 
~T 

Hence,  the  compound  fraction  is  7^.     Ans. 

Reduction  of  Fractions  to  Decimals. — Annex  ciphers  to 
the  numerator,  and  divide  by  the  denominator  and  point: 
off  as  many  decimals  places  in  the  quotient  as  there  are 
ciphers  used. 

Example. — Reduce  y^g  to  decimals. 

Solution. — 

1  6  )  9.0  0  0  0  (  .5  6  2  5.     Ans. 
80 

foo 

_9_6 

~lo 

32 
80 
80 


ARITHMETIC  15 

TABLE  OF  FRACTIONS  REDUCED  TO  DECIMALS 


«^ 

.015625 

^ 

.265625 

If 

.515625 

.765625 

.03125 

9 

.28125 

.53125 

.78125 

3 

.046875 

19 

.296875 

35 

.546875 

ti 

.796875 

TB 

.0625   ' 

^t 

.3i25 

T% 

.5625 

\l 

.8125 

t 

.078125 

jl 

.328125 

If 

.578125 

U 

.828125 

.09375 

.34375 

.59375 

H 

.84375 

W 

.109375 

II 

.359375 

if 

.609375 

il 

.859375 

1 

.125 

1 

.375 

1 

.625 

I 

.875 

ix 

.140625 

li 

.390625 

41 

.640625 

If 

.8Q0625 

6 

.lo625 

.40625 

§^ 

.65625 

.90625 

H 

.171875 

II 

.421875 

B5 

.671875 

II 

.921875 

A 

.1875 

TB 

.4375 

ii 

.6875 

TB 

.9375 

li 

.203125 

II 

.453125 

11 

.703125 

li 

.953125 

S 

.21875 

15 

.46875 

|3 

.71875 

M 

.96875 

II 

.234375 

li 

.484375 

ll 

.734375 

II 

.984375 

\ 

.25 

h 

.5 

i 

.75 

' 

1.0000 

Decimal   fractions  have   for   their    denominators   10   or   a 
power  qi  10,  but  the  denominator  is  usually  omitted.     Thus, 

.i  =  t'<t;  .01  =  1^;  .ooi=ToW;  etc 

Addition  of  Decimals. — Place  the  numbers  in  a  column 
with  whole  numbers  under  whole   numbers,   tenths  under 
tenths,  hundredths  under  hundredths,  etc.,  and  proceed  as 
in  simple  addition,  placing   the  decimal   point  in  the  sum 
directly  under  the  points  above.     Thus, 
.00  7  5 
.63  00 
1.0  600 
1  7.93  4  2 


1  9.63  1  7 


Subtraction  of  Decimals. — Arrange  the  figures  as  in  addi- 
tion, and  proceed  as  in  simple  subtraction.     Thus, 
5.9  8  9  7  8 
3.2  8  6  94 

2.682  84 


16  ARITHMETIC 

Multiplication  of  Decimals, — Proceed  .as  in  simple  multi- 
plication, pointing?  off  as  many  decimal  places  in  the  result 
as  there  are  decimal  places  in  both  multiplicand  and  multi- 
plier.    Thus, 

4.6  7  53  1 

.0  5  3 


1402593 
2337655 
.24779143 


Division  of  Decimals. — Proceed  as  in  simple  division  and 
point  off  as  many  decimal  places  in  the  quotient  as  the 
number  of  decimal  places  in  the  dividend  exceeds  those  in 
the  divisor. 

£.ramp/^.— Divide  4.7  5  6  by  3.3. 
Solution.—    3.3  )  4.7  5  6  0  0  (  1.4  4  1  2-     Ans. 
3^ 
1  45 
1  32 
136 
1  32 
40 

70 
6^ 

4 
Example— Divide  .006  by  20. 
Solution.—     2  0  )  .0  0  6  0  (  .0  0  0  3.     Ans. 
60 


PROPORTION 
SIMPLE   PROPORTION,   OR  SINGLE   RULE   OF  THREE 

A  proportion  is  an  expression  of  equality  between  equal 
ratios;  thus  the  ratio  of  10  to  5  =  the  ratio  of  4  to  2,  and  is 
expressed  thus:     10:5  =  4:2. 

There  are  four  terms  in  proportion.  The  first  and  last 
are  the  extremes,  and  the  second  and  third  are  the  means. 


ARITHMETIC  17 

Quantities  are  in  proportion  by  alternation  when  ante- 
cedent is  compared  with  antecedent  and  consequent  with 
consequent.     Thus,  if  10:5  =  4:2,  then  10:4  =  5:2. 

Quantities  are  in  proportion  by  inversion  when  antecedents 
are  made  consequents  and  the  consequents  antecedents. 
Thus,  if  10:5  =  4:2,  then  5:10  =  2:4. 

In  any  proportion,  the  product  of  the  means  will  equal 
the  product  of  the  extremes.  Thus,  if  10:5  =  4:2,  then 
5X4  =  10X2. 

A  mean  proportional  between  two  quantities  equals  the 
square  root  of  their  products.  Thus,  a  mean  proportional 
between  12  and  3  is  the  square  root  of  12X3  or  6. 

If  the  two  means  and  one  extreme  of  a  proportion  are 
given,  we  find  the  other  extreme  by  dividing  the  product 
of  the  means  by  the  given  extreme.  Thus,  10:5  =  4: (?) 
then  4X5-HlO  =  2,  and  the  proportion  is  10:5  =  4:2. 

If  the  two  extremes  and  one  mean  are  given,  we  find 
the  other  mean  by  dividing  the  product  of  the  extreme 
by  the  given  mean.  Thus,  10:  (?)  =4:2,  then  10X2-^4  =  5, 
and  the  proportion  is  10:5  =  4:2. 

Example. — If  6  men  unload  30  cars  of  ballast  in  a  day, 
how  many  cars  will  10  men  unload? 

Solution. — As  10  men  will  unload  more  than  6  men,  the 
second  term  of  the  proportion  must  be  greater  than  the 
first;  hence,  6:10  =  30  :  ('),  then. 

10X30-^-6  =  50  cars.     Ans. 

COMPOUND  PROPORTION,  OR  DOUBLE  RULE  OF 
THREE 

1.  The  product  of  the  simple  ratios  of  the  first  couplet 
equals  the  product  of  the  simple  ratios  of  the  second  couplet. 
Thus, 

(4:12)        f5:101  ^1       7  =  5^y6 
17:14/        16:18/      12^14     10      18' 

2.  The  product  of  all  the  terms  in  the  extremes  equals 
the  product  of  all  the  terms  in  the  means.     Thus,  in 

f4:12l  _  f5:101 
17:14/       16:18/ 
we  have,  4X7X10X18  =  12X14X5X6 


IS  ARITHMETIC 

3.  Any  term  in  either  extreme  equals  the  product  of  the 
means  divided  by  the  product  of  the  other  terms  in  the 
extremes.     Thus,  in  the  same  proportion,  we  have 

_  5X6X12X14 
7X10X18 

4.  Any  term  in  either  mean  equals  the  product  of  the 
extremes  divided  by  the  product  of  the  other  terms  in  the 
means.     Thus,  in 


f4:121  _  r5:101 
17:14/       16:18/ 


we  have,  5  =  (4X  7X  lOX  18)  ^(6X  12X  14) 

Rule. — I.  Put  the  required  quantity  for  the  first  term  and 
the  similar  known  quantity  for  the  second  term,  and  form  ratios 
with  each  pair  of  similar  quantities  for  the  second  couplet,  as 
if  the  result  depended  on  each  pctir  and  the  second  term: 

II.  Find  the  required  term  hy  dividing  the  product  of  the 
means  by  the  product  of  the  fourth  terms. 

Example. — If  4  men  can  earn  $24  in  7  da.,  how  much  can 
14  men  earn  in  12  da.? 

Solution.—  Sum  :  $24 


fl4:4| 
112:7/ 


^            24X14X12     ^,^.        . 
Sum  = ■ — =$144.     Ans. 

4  X  / 

Example. — If  12  men,  in  35  da.,  can  build  a  wall  140  rd. 
lonj?,  6  ft.  high,  how  many  men  can,  in  40  da.,  build  a  wall 
of  the  same  thickness  144  rd.  long,  5  ft.  high? 

Solution. — 


fl2  :  ()■»  ^f  140:1441  ^  12X35X144X5 
135:40/       10:5/  40X140X6 


-;>.r"-~-  =  9.     Ans. 


INVOLUTION 

To  Square  a  Number. —  Multiply  the  number  by  itself. 
Thus,  the  sfiuare  of  4  =  4  \  4,  or  16. 

To  Cube  a  Number. — Multiply  the  square  of  the  number 
In-  tbf  nnm}.fr       Thus,  the  cube  of  4  =  16 X 4  =  64. 


ARITHMETIC  19 

To  Find  the  Fourth  Power  of  a  Number. — Multiply  the 
cube  by  the  number.  Thus,  the  fourth  power  of  4  =  64X4 
=  256. 

To  Raise  a  Number  to  the  Sixth  Power. — Square  its  cube. 

To  Raise  a  Number  to  the  Twelfth  Power. — Square  its 
sixth  power. 

(See  logarithms  for  a  shorter  method.) 


EVOLUTION 

Rule  for  Extracting  Any  Root  of  Any  Number. — I.  Point 
off  the  number  into  periods  that  shall  contain  as  many  figures  as 
there  are  units  in  the  index  of  the  root,  beginning  with  the 
decimal  point. 

II.  Find  the  largest  number  that,  when  raised  to  the  power 
indicated  by  an  exponent  having  as  many  units  as  the  index 
figure  of  the  root,  does  not  exceed  the  first  period;  the  number 
thus  obtained  will  be  the  first  figure  of  the  root. 

III.  Raise  the  first  figure  of  the  root  to  the  power  indicated 
by  an  exponent  having  as  many  units  as  the  index  figure  of 
the  root,  and  subtract  the  result  from  the  first  period;  annex  the 
first  figure  of  the  second  period  to  the  remainder,  and  call 
the  result  the  first  dividend. 

IV.  Raise  the  first  figure  of  the  root  to  that  power  indicated 
by  an  exponent  that  has  one  less  unit  than  the  index  figure  of 
the  root;  multiply  the  result  by  the  index  figure,  and  call  the 
product  the  first  divisor. 

V.  Divide  the  first  dividend  by  the  first  divisor  and  obtain 
two  figures  of  the  quotient  the  second  of  which  may  be  a  decimal. 
If  the  quotient  is  less  than  10  and  the  second  figure  is  o  or  a 
greater  number,  write  the  first  figure  of  the  quotient  as  the 
second  figure  of  the  root;  if  less  than  5,  subtract  1  from  the  first 
figure  of  the  quotient  for  the  second  figure  of  the  root.  If  the 
divisor  is  greater  than  the  dividend,  write  a  cipher  for  the  second 
figure  of  the  root.  If  the  dividend  contains  the  divisor  10  or 
more  times,  try  9  for  the  second  figure  of  the  root;  if  9  is  also 
too  large,  try  8;  and  so  on. 

VI.  Raise  that  portion  of  the  root  already  found  to  the 
power  indicated  by  an  exponent  having  as  many  units  as  the 


20  ARITHMETIC 

index  figure;  subtract  the  result  from  the  -first  two  periods; 
annex  the  first  figure  of  the  third  period  to  the  remainder,  and 
call  the  result  the  second  dividend. 

VII.  Raise  that  portion  of  the  root  already  found  to  the 
power  indicated  by  an  exponent  having  one  less  unit  than  the 
index  figure;  multiply  the  result  by  the  index  figure,  and  call 
the  product  the  second  divisor.  Divide  the  second  dividend 
by  the  second  divisor  {as  described  in  V)  for  the  third  figure 
of  the  root. 

VIII.  Proceed  as  in  VI  and  VII  for  the  fourth  figure  of  the 
root,  and  so  on  for  more  figures,  if  desired. 

NoTB.— The  result  obtained  in  V  may  be  too  large  or  too  small;  if  so,  it  will 
be  made  evident  in  VI  when  getting  the  second  dividend,  and  a  smaller  (or 
larger)  number  must  be  used  for  the  second  figure  of  the  root.  If  the  given 
number  whose  root  is  to  be  found  is  wholly  decimal,  take  care  that  the  first 
period  contains  as  many  figures  (annexing  ciphers,  if  necessary)  as  there  are 
units  in  the  index  figure  of  the  root.  Thus,  in  extracting  the  seventh  root  of 
.02794,  the  first  period  would  be  .0279400,  and  the  remaining  periods,  cipher 
periods. 

Example. — Extract,  the  square  root  of  1,971.14. 
Solution.—  1971. '14(44.398 

42  =  16 

1st  divisor  =  4X2  =8)37  1st  dividend 

4.6;  hence,  4  is  second  figure 

of  root 
1971  1st  and  2d  periods 

442  =  1936 
2d  divisor  =  44 X 2  =88)'~351         2d  dividend 

3.9;         hence.  3   is  third   figure 
of  root 
197114        1st,  2d,  and  3d  periods 
4432=  1962^ 

3d  divisor  =  443X2  =886) 8650     3d  dividend 

9.76  +  ;  hence.  9  and  8  are,  re- 
spectively, the  fourth 
and    fifth    figures    of 
root. 
Required  root  is  44.398.     Ans. 
Example. — Extract  the  cube  root  of  2,571.14. 


ARI'l  HMETIC 

21 

Solution.—                               2'571.'14(13.69  + 

13=    1 

1st  divisor  =  12X3  =3)15 

1st  dividend 

5.0 

2571 
133=  2197 
2d  divisor  =  132X3  =507)  3741 

It  is  evident  that  4 
as  the  second  figure 
of    the    root    is    too 
large;  hence,  use  3 
1st  and  2d  periods 

2d  dividend 

7.3 
2571140 
13.63=  2515456 

hence,  6  is  third  fig- 
ure of  root 

1st,      2d,      and     3d 
periods 

556840   3d  dividend 


10.         hence,  9    is    fourth 
figure  of  root 
Required  root  is  13.69 -h.     Ans. 

Example.—     ^909,203,700,718,879,776  =  ' 

First      Second    Third    Fourth 
Period     Period   Period    Period 
Solution.—  909        20370     07188  79776  (  3906 

35  =  243 
1st  divisor  =  3^  X  5  =  405)6662     1st  dividend 

16  + 
Since  16  is  greater  than  10,  we  try  9. 

90920370  15/  and  2d  periods 
395  =  90224199 
2d  divisor  =  39^  X  5  =  11567205)        6961710  2d  dividend 

0 
Since  the  divisor  is  greater  than  the  dividend,  we  write  0 
for  the  third  figure  of  the  root. 

9092037007188  1^^  2d,  3d  pe- 
3905  =  9022419900000  riods 

3d  divisor  =  1  =i  15672050000)    696171071887  3d  dividend 

^'"'"^'^  6  +  .     Trv6. 

909203700718879776  1st,  2d,  3d,  and  4th  periods 
39065  =  909203700718879776 


22  ARITHMETIC 

NoTB.— After  having  obtained  the  first  three  figures  of  the  root,  the  first  fig- 
ure of  the  quotient,  obtained  by  dividing  a  dividend  by  its  corresponding 
divisor,  will  always  be  the  next  figure  of  the  root.  If  the  given  number  is  not 
a  perfect  power,  find  three  figures  of  the  quotient  when  dividing  the  third  divi- 
dend  by  the  third  divisor,  and  -write  ttie  first  and  second  figures  (increasing  the 
second  figure  by  1  if  the  third  figure  is  5  or  a  greater  digit)  as  the  fourth  and 
fifth  figures  of  the  root.  It  is  seldom  that  more  than  five  figures  of  the  root  are 
required. 


PERCENTAGE 

Percentage  means  by  or  on  the  hundred.     Thus,  1  %  =  1  on 
100,  3%  =3  on  100,  5%  =  5  on  100,  etc. 

To  Find  the  Percentage,  Having  the  Rate  and  the  Base. 
Multiply   the   base   by   the   rate   expressed   in   hundredths. 
Thus.  6%  of  1.930  is  found  thus: 
1930 
.06 


115.80 


To  Find  the  Amount,  Having  the  Base  and  Rate. — Multiply 
the  base  by  1  plus  the  rate.     Thus,  to  find  the  amount  of 
11,930  for  1  year,  at  6%,  we  multiply  1,930  by  1.06. 
$1,930  XI. 06  =  $2,045.80 

To  Find  the  Base,  Having  the  Rate  and  the  Percentage. 
Divide  the  percentage  by  the  rate  to  find  the  base.  Thus, 
if  the  rate  is  6%  and  the  percentage  is  115.80,  the  base  is 
115.80^.06  =  1,930. 

To  Find  the  Rate,  Having  the  Percentage  and  the  Base. 
Divide  the  percentage  by  the  base.  Thus,  if  the  percentage 
is  115.80  and  the  base  1,930,  the  rate  equals  115.80-1-1,930 
=  .06,  or  6%. 


MENSURATION 

In  the  following  formulas,  the  letters  have  the  meanings 
here  given,  unless  otherwise  stated: 
Z?  =  larger  diameter; 
d  =  smaller  diameter; 
R  =  radius  corresponding  to  D; 
r  ■=  radius  corresponding  to  d; 
p  =  perimeter  or  circumference; 


ARITHMETIC 


23 


C  =area  of  convex  surface  =  area  of  flat  surface  that  can  be 
rolled  into  the  shape  shown; 

5=  area  of  entire  surf  ace  =  C  +  area  of  the  end  or  ends; 

i4  =  area  of  plane  figure; 

ir  =3.1416,  nearly  =  ratio  of  any  circumference  to  its  diam- 
eter; 

V  =  volume  of  solid; 

The  other  letters  used  will  be  found  on  the  cuts. 


CIRCLE 

^  =  n-rf  =  3.1416  d 
^  =  27rr  =  6.2832  r 
/)  =  2  Vi!^=  3.5449  Va 


P- 


2  A      4  A 


d  =  ^  = 


n      3.1416 


=  .3183p 


rf  =  2^^  =  1.1284  VI 


.2832 


=  .1592  p 


r=  yj~  =  .o642<A 

^  =  ^  =  .7854  ci2 
4 

^  =  ^r2  =  3.1416r2 
A      Pr     pd 


TRIANGLES 


D  =  B  +  C  £+B4-C  =  180" 

B  =  D-C  £'  +  3  +  0=12,0° 

E'  =  E  B'  =  B. 

The  above  letters  refer  to  angles. 


24  ARITHMETIC 

For  a  right  triangle,  c  being  the  hypotenuse, 


c=\a2  +  62 


c  =  length  of  side  opposite  an 
acute  angle  of  an  oblique  triangle 
c=>/o2  +  62^26i 

c  =  length  of  side  opposite  an  obtuse  angle 
of  an  oblique  triangle. 

h=Sa2-e2 

For  a  triangle  inscribed  in  a  semicircle;  i.  e.,  any  right 
triangle, 

c:b  =  a:h 

u—  ^_£f 
c       a 

a.b  +  e  =  e:a  =  h:c 


L 


For  any  triangle, 


A  fr^    11.7 


^4V.-(-±g-/ 


X 


RECTANGLE  AND  PARALLELOGRAM 

A=ab 


A  =  b^c^-b' 


TRAPEZOID 

A  =  ih(a  +  b) 


ARITHMETIC 


25 


TRAPEZIUM 

Divide  into  two  triangles  and  a  trapezoid. 

or,  A  =  ^[hh'  +  ck  +  a(h'  +  h)] 

Or.  divide  into  two  triangles  by  drawing 
a  diagonal.     Consider  the  diagonal  as  the 
base  of  both  triangles;  call  its  length  /; 
call  the  altitudes  of  the  triangles  hi  and  /12;  then 
A  =  hl{hi+h2) 


n(D  +  d) 


ELLIPSE 

D 


64 


3(^ 


— (g^^): 


A  =iDd=. 7854  Dd 
4 


€S 


SECTOR 


A  =  ^lr 
._nr2E 

/  =  length  of  arc 


008727  r2£ 


SEGMENT 

A  =  Wr-cir-h)] 


A  = 


TT^E 

360 


|(r-/.) 


•  The  perimeter  of  an  ellipse  cannot  be  exactly  determined  without  a  very 
elaborate  calculation,  and  this  formula  is  merely  an  approximation  giTing  clos* 
results. 


26 


ARITHMETIC 


CYLINDER 

C  =  -ndh 

S  =  2nrh  +  2irr^ 

V  =  nr2h=.'^d2h 
4 

y  =  |^  =  . 0796^2;, 


FRUSTUM  OF  CYLINDER 

h  =  i  sum  of  greatest  and  least  heights 
C  =  ph  =  ndh 

S  =  ndh  +  -zd^  + area  of  elliptical  top 


Ah  =  -d2h 
4 


PRISM  OR  PARALLELOPIPED 

C=Ph 
S=Ph  +  2A 
V  =  Ah 
For    prisms  with   regular  polygon  as 
bases,  P  =  length  of  one  side  X  number  of  sides. 

To  obtain  area  of  base,  if  it  is  a  polygon,  divide  it  into  tri- 
angles, and  find  sum  of  partial  areas. 


FRUSTUM  OF  PRISM 

If  a  section   perpendicular  to  the  edges  is  a 
triangle,  square,  parallelogram,  or  regular  poly- 

,,     sum  of  lengths  of  edges^,  ,      .   ,  . 

gon,  V  = —  ,— , ^^Xarea    of    nght 

number  ot  edges 
section. 


SPHERE 

5  =  ,r(i^  =  4,rr2  =  l2.5664r2 
r -J7rd3  =  j7rr3  =  . 5236^3  =  4. 1888r« 


LOGARITHMS 
CIRCULAR  RING 

Z)  =  mean  diameter; 

/^  =  mean  radius. 

S  =  47r2/?r  =  9.8696Drf 
V  =  2rr2i?r2  =  2.4674L'd2 


WEDGE 


LOGARITHMS 

EXPONENTS 

By  the  use  of  logarithms,  the  processes  of  multiplication, 
division,  involution,  and  evolution  are  greatly  shortened,  and 
some  operations  may  be  performed  that  would  be  impossible 
without  them.  Ordinary  logarithms  cannot  be  applied  to 
addition  and  subtraction. 

The  logarithm  of  a  number  is  that  exponent  by  which  some 
fixed  number,  called  the  base,  must  be  affected  in  order  to 
equal  the  number.  Any  number  may  be  taken  as  the  base. 
Suppose  we  choose  4.  Then  the  logarithm  of  16  is  2,  because 
2  is  the  exponent  by  which  4  (the  base)  must  be  affected  in 
order  to  equal  16,  since  42  =  16.  In  this  case,  instead  of 
reading  42  as  4  square,  read  it  4  exponent  2.  With  the  same 
base,  the  logarithms  of  64  and  8  would  be  3  and  1.5,  respect- 
ively, since  43  =  64,  and  4i-5  =  4'  =  8.  In  these  cases,  as  in 
the  preceding,  read  4^  and  4}-^  as  4  exponent  3,  and  4  expo- 
nent 1.5,  respectively. 

Although  any  positive  number  except  1  can  be  used  as  a 
base  and  a  table  of  logarithms  calculated,  but  two  numbers 
have  ever  been  employed.  For  all  arithmetical  operations 
(except  addition  and  subtraction)  the  logarithms  used  are 
called  the  Briggs,  or  common,  logarithms,  and  the  base  used 
is  10.  In  abstract  mathematical  analysis,  the  logarithms  used 
are  variously  called  hyperbolic,  Napierian,  or  natural  loga- 
rithms, and  the  base  is  2.718281828-1- .  The  common  loga- 
rithm of  any  number  may  be  converted  into  a  Napierian 


28  LOGARITHMS 

logarithm  by  multiplying  the  common  logarithm  by 
2.30258509  + ,  which  is  usually  expressed  as  2.3026,  and 
sometimes  as  2.3.  Only  the  common  system  of  logarithms 
will  be  considered  here. 

Since  in  the  common  system  the  base  is  10,  it  follows  that, 
since  10i  =  10,  102  =  100,  103  =  1,000,  etc.,  the  logarithm 
(exponent)  of  10  is  1,  of  100  is  2,  of  1,000  is  3,  etc.  For  the 
sake  of  brevity  in  writing,  the  words  "logarithm  of"  are 
abbreviated  to  "log."  Thus,  instead  of  writing  logarithm 
of  100  =  2,  write  log  100  =  2.  When  speaking,  however,  the 
words  for  which  "log"  stands  should  always  be  pronounced 
in  full. 

From  the  above  it  will  be  seen  that,  when  the  base  is  10, 
since  10°=         1,  the  exponent  O  =  log  1; 

since  10^=  10,  the  exponent  1  =  log  10; 
since  102=  100,  the  exponent  2  =  log  100; 
since  103=1,000,  the  exponent  3  =  log  1,000;  etc. 

Also, 
since  10—^  =  iV    =    -1 .      the  exponent  —  1  =log  .1 ; 
since  10— 2  =  xJ5   =01,    the  exponent  — 2  =  log  .01; 
since  10-3  =  -^^5=  001,  the  exponent- 3  =  log  .001;  etc. 

From  this  it  will  be  seen  that  the  logarithms  of  exact 
powers  of  10  and  of  decimals  like  .1,  .01,  and  .001  are  the 
whole  numbers  1,  2,  3,  etc.,  and  —1,  —2,  —3,  etc.,  respect- 
ively. Only  numbers  consisting  of  1  and  one  or  more  ciphers 
have  whole  numbers  for  logarithms. 

Now,  it  is  evident  that,  to  produce  a  number  between  1 
and  10,  the  exponent  of  10  must  be  a  fraction;  to  produce 
a  number  between  10  and  100,  it  must  be  1  plus  a  fraction; 
to  produce  a  number  between  100  and  1,000,  it  must  be  2 
plus  a  fraction,  etc.  Hence,  the  logarithm  of  any  number 
between  1  and  10  is  a  fraction;  of  any  number  between  10 
and  100,  1  plus  a  fraction;  of  any  number  between  100  and 
1,000,  2  plus  a  fraction,  etc.  A  logarithm,  therefore,  usually 
consists  of  two  parts;  a  whole  number,  called  the  charac- 
teristic, and  a  fraction,  called  the  mantissa.  The  mantissa  is 
always  expressed  as  a  decimal.  For  example,  to  produce  20, 
10  must  have  an  exponent  of  approximately  1.30103,  or 
101.30103  =-20,  very  nearly,  the  degree  of  exactness  depending 


LOGARITHMS  29 

on  the  number  of  decimal  places  used.  Hence,  log  20 
=  1.30103,  1  being  the  characteristic,  and  .30103,  the 
mantissa. 

Referring  to  the  second  part  of  the  preceding  table,  it  is 
clear  that  the  logarithms  of  all  numbers  less  than  1  are 
negative,  the  logarithms  of  those  between  1  and  .1  being  —1 
plus  a  fraction.  For,  since  log  .1=  —1,  the  logarithms  of 
.2,  .3,  etc.  (which  are  all  greater  than  .1,  but  less  than  1) 
must  be  greater  than  —1;  i.  e.,  they  must  equal  —1  plus  a 
fraction.  For  the  same  reason,  to  produce  a  number  between 
.1  and  .01,  the  logarithm  (exponent  of  10)  would  be  equal  to 
—  2  plus  a  fraction,  and  for  a  number  between  .01  and  .001, 
it  would  be  equal  to  —3  plus  a  fraction.  Hence,  the  loga- 
rithm of  any  number  between  1  and  .01  has  a  negative 
characteristic  qf  1  and  a  positive  mantissa;  of  a  number 
between  .1  and  .01,  a  negative  characteristic  of  2  and  a 
positive  mantissa;  of  a  number  between  .01  and  .001,  a  nega- 
tive characteristic  of  3  and  a  positive  mantissa;  of  a  number 
between  .001  and  .0001,  a  negative  characteristic  of  4  and  a 
positive  mantissa,  etc.  The  negative  characteristics  are  dis- 
tinguished from  the  positive  by  the  —  sign  written  over  the 
characteristic.     Thus,  3  indicates  that  3  is  negative. 

It  must  be  remembered  that  in  all  cases  the  mantissa  is 
positive.  Thus,' thelogarithm  1.30103  means  4-1  -f. 30103, 
and  the  logarithm  1.30103  means  -1  4- .30103.  Were  the 
minus  sign  written  in  front  of  the  characteristic,  it  would 
indicate  that  the  entire  logarithm  was  negative.  Thus, 
-1.30103=    -1   -.30103. 

Rule  for  Characteristic. — Starting  from  the  unit  figure, 
count  the  number  of  places  to  the  first  (left-hand)  digit  of 
the  given  number,  calling  unit's  place  zero;  the  number  of 
places  thus  counted  will  be  the  required  characteristic.  If 
the  first  digit  lies  to  the  left  of  the  unit  figure,  the  character- 
istic is  positive;  if  to  the  right,  negative.  If  the  first  digit  of 
the  number  is  the  unit  figure,  the  characteristic  is  0.  Thus, 
the  characteristic  of  the  logarithm  of  4,826  is  3,  since  the 
first  digit,  4,  lies  in  the  3d  place  to  the  left  of  the  unit  figure,^. 
The  characteristic  of  the  logarithm  of  0.0000072  is  -6  or  6", 
since  the  first  digit,  7,  lies  in  the  6th  place  to  the  right  of  the 


30  LOGARITHMS 

unit  figure.  The  characteristic  of  the  logarithm  of  4.391  is  0, 
since  4  is  both  the  first  digit  of  the  number  and  also  the 
unit  figure. 

TO  FIND  THE  LOGARITHM  OF  A  NUMBER 

To  aid  in  obtaining  the  mantissa  of  logarithms,  tables  of 
logarithms  have  been  calculated,  some  of  which  are  very 
elaborate  and  convenient.  In  the  Table  of  Logarithms,  the 
mantissas  of  the  logarithms  of  numbers  from  1  to  9,999  are 
given  to  five  places  of  decimals.  The  mantissas  of  logarithms 
of  larger  numbers  can  be  found  by  interpolation.  The  table 
contains  the  mantissas  only;  the  characteristics  may  be  easily 
found  by  the  preceding  rule. 

The  table  depends  on  the  principle,  which  will  be 
explained  later,  that  all  numbers  having  the  same  figures 
in  the  same  order  have  the  same  mantissa,  without  regard  to 
the  position  of  the  decimal  point,  which  affects  the  charac- 
teristic only.  To  illustrate,  if  log  206  =  2^1387,  then, 
log  20.6  =  1.31387;  log  .206   =j..31387; 

log  2.06=    .31387;  log  .0206  =  2.31387;  etc. 

To  find  the  logarithm  of  a  number  not  having  more  than 
four  figures : 

Rule. — Find  the  first  three  significant  figures  of  the  number 
whose  logarithm  is  desired,  in  the  left-hand  column;  find  the 
fourth  figure  in  the  column  at  the  top  (or  bottom)  of  the  page; 
and  in  the  column  under  (or  above)  this  figure,  and  opposite  the 
first  three  figures  previously  found,  will  be  the  mantissa  or 
decimal  part  of  the  logarithm.  The  characteristic  being  found 
as  previously  described,  write  it  at  the  left  of  the  mantissa,  and 
the  resulting  expression  will  be  the  logarithm  of  the  required 
number. 

Example. — Find  from  the  table  the  logarithm:  (a)  of  476; 
(fc)  of  25.47;  (c)  of  1.073;  (d)  of  .06313. 

Solution. — (a)  In  order  to  economize  space  and  make 
the  labor  of  finding  the  logarithms  easier,  the  first  two  figures 
of  the  mantissa  are  given  only  in  the  column  headed  0.  The 
last  three  figures  of  the  mantissa,  opposite  476  in  the  column 
headed  N  (N  stands  for  number),  are  761,  found  in  the 
column  headed  0;  glancing  upwards,  we  find  the  first  two 


LOGARITHMS  31 

figures  of  the  mantissa,  viz.,  67.     The  characteristic  is  2; 
hence,  log  476  =  2.67761.     Ans. 

NoTB.— Since  all  numbers  in  the  table  are  decimal  fractions,  the  decimal 
point  is  omitted  throughout;  this  is  customary  in  all  tables  of  logarithms. 

(b)  To  find  the  logarithm  of  25.47,  we  find  the  first  three 
figures,  254,  in  the  column  headed  N,  and  on  the  same  hori- 
zontal line,  under  the  column  headed  7  (the  fourth  figure  of 
the  given  number),  will  be  found  the  last  three  figures  of 
the  mantissa,  viz.,  603.  The  first  two  figures  are  evidently  40, 
and  the  characteristic  is  1;  hence,  log  25.47  =  1.40603.     Ans. 

(c)  For  1.073;  in  the  column  headed  3,  opposite  107  in 
the  column  headed  N,  the  last  three  figures  of  the  mantissa 
are  found,  in  the  usual  manner,  to  be  060.  It  will  be  noticed 
that  these  figures  are  printed  *060,  the  star  meaning  that 
instead  of  glancing  upwards  in  the  column  headed  0,  and 
taking  02  for  the  first  two  figures,  we  must  glance  downwards 
and  take  the  two  figures  opposite  the  number  108,  in  the 
left-hand  column,  i.  e.,  03.  The  characteristic  being  0,  log 
1.073=0.03060,  or,  more  simply,  .03060.     Ans. 

(d)  For  .06313;  the  last  three  figures  of  the  mantissa  are 
found  opposite  631,  in  column  headed  3,  to  be  024.  In  this 
case,  the  first  two  figures  occur  in  the  same  row,  and  are  80. 
Since  the  characteristic  is  2,  log  .06313  =  2.80024.     Ans. 

If  the  original  number  contains  but  one  digit  (a  cipher  is 
not  a  digit),  annex  mentally  two  ciphers  to  the  right  of  the 
digit;  if  the  number  contains  but  two  digits  (with  no  ciphers 
between,  as  in  4,008),  annex  mentally  one  cipher  on  the 
right  before  seeking  the  mantissas.  Thus,  if  the  logarithm  of 
7  is  wanted,  seek  the  mantissa  for  700,  which  is  .84510;  or,  if 
the  logarithm  of  48  is  wanted,  seek  the  mantissa  for  480, 
which  is  .68124.  Or,  find  the  mantissa  of  logarithms  of 
numbers  between  0  and  100,  on  the  first  page  of  the  tables. 

The  process  of  finding  the  logarithm  of  a  number  from 
the  table  is  technically  called  taking  out  the  logarithm. 

To  take  out  the  logarithm  of  a  number  consisting  of  more 
than  four  figures,  it  is  inexpedient  to  use  more  than  five 
figures  of  the  number  when  using  five-place  logarithms  (the 
logarithms  given  in  the  accompanying  table  are  five-place). 
Hence,  if  the  number  consists  of  more  than  five  figures  and 


32  LOGARITHMS 

the  sixth  figure  is  less  than  5,  replace  all  figures  after  the  fifth 
with  ciphers;  if  the  sixth  figure  is  5  or  greater,  increase  the 
fifth  figure  by  1  and  replace  the  remaining  figures  with 
ciphers.  Thus,  if  the  number  is  31, 415, 926,  find  the  logarithm 
of  31,416,000;  if  31.415,426,  find  the  logarithm  of  31,415,000. 

Example— Yind  log  31,416. 

Solution. — Find  the  mantissa  of  the  logarithm  of  the  first 
four  figures,  as  explained  above.  This  is,  in  the  present  case, 
.49707.  Now,  subtract  the  number  in  the  column  headed  1, 
opposite  314  (the  first  three  figures  of  the  given  number), 
from  the  next  greater  consecutive  number,  in  this  case  721, 
in  the  column  headed  2.  721—707  =  14;  this  number  is 
called  the  difference.  At  the  extreme  right  of  the  page  will 
be  found  a  secondary  table  headed  P.  P.,  and  at  the  top  of 
one  of  these  columns,  in  this  table,  in  bold-face  type,  wall  be 
found  the  difference.  It  will  be  noticed  that  each  column  is 
divided  into  two  parts  by  a  vertical  line,  and  that  the  figures 
on  the  left  of  this  line  run  in  sequence  from  1  to  9.  Consult- 
ing the  difference  column  headed  14,  we  see  opposite  the 
number  6  (6  is  the  last  or  fifth  figure  of  the  number  whose 
logarithm  we  are  taking  out)  the  number  8.4,  snd  we  add 
this  number  to  the  mantissa,  found  above,  disregarding  the 
decimal  point  in  the  mantissa,  obtaining  49,707  +  8.4 
=  49,715.4.  Now,  since  4  is  less  than  5,  we  reject  it,  and 
obtain  for  our  complete  mantissa  .49715.  Since  the  charac- 
teristic of  the  logarithm  of  31.416  is  4,  log  31,416  =  4.49715. 

Ans. 
Example.— Find  log  380.93. 

Solution. — Proceeding  in  exactly  the  same  manner  as 
above,  the  mantissa  for  3,809  is  58,081  (the  star  directs  us  to 
take  58  instead  of  57  for  the  first  two  figures);  the  next 
greater  mantissa  is  58,092,  found  in  the  column  headed  0, 
opposite  381  in  column  headed  N.  The  difference  is  092 
—  081  =  11.  Looking  in  the  section  headed  P.  P.  for  column 
headed  11,  we  find  opposite  3,  3.3;  neglecting  the  .3,  since  it 
is  less  than  5,  3  is  the  amount  to  be  added  to  the  mantissa  of 
the  logarithm  of  3,809  to  form  the  logarithm  of  38,093. 
Hence,  58,081-1-3  =  58,084.  and  since  the  characteristic  is  2. 
log  380.93  =  2.58084.     Ans. 


LOGARITHMS  33 

Example.— ¥m6.  log  1,296,728. 

Solution. — Since  this  number  consists  of  more  than  five 
figures  and  the  sixth  figure  is  less  than  5,  we  find  the  loga- 
rithm of  1,296,700  and  call  it  the  logarithm  of  1,296,728. 
The  mantissa  of  log  1,296  is  found  to  be  11,261.  The  differ- 
ence is  294-261  =  33.  Looking  in  the  P.  P.  section  for  col- 
umn headed  33,  we  find  opposite  7,  on  the  extreme  right, 
23.1;  neglecting  the  .1,  the  amount  to  be  added  to  the  above 
mantissa  is  23.  Hence,  the  mantissa  of  log  1,296,728 
=  11,261+23  =  11,284;  since  the  characteristic  is  6,  log 
1,296,728  =  6.11284.     Ans. 

Example. — Find  log  89.126. 

Solution. — Log  89.12  =  1.94998.  Difference  between  this 
and  log  80.13  =  1.95002-1.94998  =  4.  The  P.  P.  (propor- 
tional part)  for  the  fifth  figure  of  the  number  6  is  2.4,  or  2. 
Hence,  log  89.126  =  1.94998 +  .00002  =  1.95000.     Ans. 

Example. — Find  log  .096725. 

Solution.—     Log  .09672=2.98552.     Difference  =4. 
P.  P.  for  5=  2 

Hence,  log  .096725  =  2.98554.     Ans. 

To  find  the  logarithm  of  a  number  consisting  of  five  or 
more  figures: 

Rule. — I.  If  the  number  consists  of  more  than  five  figures 
and  the  sixth  figure  is  5  or  greater,  increase  the  fifth  figure  by  1 
and  write  ciphers  in  place  of  the  sixth  and  remaining  figures. 

II.  Find  the  mantissa  corresponding  to  the  logarithm  of 
the  first  four  figures,  and  subtract  this  mantissa  from  the  next 
greater  mantissa  in  the  table;  the  remainder  is  the  difference. 

III.  Find  in  the  secondary  table  headed  P.  P.  a  column 
headed  by  the  same  number  as  that  just  found  for  the  difference, 
and  in  this  column,  opposite  the  number  corresponding  to  the 
fifth  figure  (or  fifth  figure  increased  by  1)  of  the  given  number 
(this  figure  is  always  situated  at  the  left  of  the  dividing  line 
of  the  column),  will  be  found  the  P.  P.  (proportional  part) 
for  that  number.  The  P.  P.  thus  found  is  to  be  added  to  the 
mantissa  fotind  in  II,  as  in  the  preceding  examples,  and  the 
result  is  the  mantissa  of  the  logarithm  of  the  given  number,  as 
nearly  as  may  be  found  with  five-place  tables. 


34  LOGARITHMS 

TO  FIND  A  NUMBER  WHOSE  LOGARITHM  IS  GIVEN 
Rule. — I.  Consider  the  mantissa  first.  Glance  along  the 
different  columns  of  the  table  which  are  headed  0,  until  the  first 
iuv  figures  of  the  mantissa  are  found.  Then,  glance  down  the 
same  column  until  the  third  figure  is  found  (or  1  less  than 
the  third  figure).  Having  found  the  first  three  figures,  glance 
to  the  right  along  the  row  in  which  they  are  situated  until  the 
last  three  figures  of  the  mantissa  are  found.  Then,  the  number 
that  heads  the  column  in  which  the  last  three  figures  of  the 
mantissa  are  found  is  the  fourth  figure  of  the  required  number, 
and  the  first  three  figures  lie  in  the  column  headed  N,  and  in 
the  same  row  in  which  lie  the  last  three  figures  of  the  mantissa. 

II.  If  the  mantissa  cannot  be  found  in  the  table,  find  the 
mantissa  that  is  nearest  to,  but  less  than,  the  given  mantissa, 
and  which  call  the  next  less  mantissa.  Subtract  the  next  less 
mantissa  from  the  next  greater  mantissa  in  the  table  to  obtain 
the  difference.  Also,  subtract  the  next  less  mantissa  from  the 
mantissa  of  the  given  logarithm,  and  call  the  remainder  the 
P.  P.  Looking  in  the  secondary  table  headed  P.  P.  for  the 
column  headed  by  the  difference  just  found,  find  the  number 
opposite  the  P.  P.  just  found  (or  the  P.  P.  corresponding  most 
nearly  to  thai  just  found);  this  number  is  the  fifth  figure  of 
the  required  number;  the  fourth  figure  will  be  found  at  the  top 
of  the  column  containing  the  next  less  mantissa,  and  the  first 
three  figures  in  the  column  headed  N  and  in  the  same  row  that 
contains  the  next  less  mantissa. 

III.  Having  found  the  figures  of  the  number  as  above 
directed,  locate  the  decimal  point  by  the  rules  for  the  character' 
istic,  annexing  ciphers  to  bring  the  number  up  to  the  required 
number  of  figures  if  the  characteristic  is  greater  than  4. 

Example. — Find  the  number  whose  logarithm  is  3.56867. 

Solution. — The  first  two  figures  of  the  mantissa  are  56; 
glancing  down  the  column,  we  find  the  third  figure,  8  (in 
connection  with  820),  opposite  370  in  the  N  column.  Glan- 
cing to  the  right  along  the  row  containing  820,  the  last" three 
figures  of  the  mantissa,  867,  are  found  in  the  column  headed 
4;  hence,  the  fourth  figure  of  the  required  number  is  4,  and 
the  first  three  figures  are  370,  making  the  figures  of  the 
required  number  3,704.     Since  the  characteristic  is  3,  there 


LOGARITHMS  35 

are  three  figures  to  the  left  of  the  unit  figure,  and  the  num- 
ber whose  logarithm  is  3.56867  is  3,704.     Ans. 

Example. — Find  the  number  whose  logarithm  is  3.56871. 

Solution. — The  mantissa  is  not  found  in  the  table.  The 
next  less  mantissa  is  56,867;  the  difference  between  this  and 
the  next  greater  mantissa  is  879  —  867  =  12,  and  the  P.  P.  is 
56,871-56,867  =  4.  Looking  in  the  P.  P.  section  for  the 
column  headed  12,  we  do  not  find  4,  but  we  do  find  3.6  and 
4.8.  Since  3.6  is  nearer  4  than  4.8,  we  take  the  number 
opposite  3.6  for  the  fifth  figure  of  the  required  number;  this 
is  3.  Hence,  the  fourth  figure  is  4;  the  first  three  figures 
370,  and  the  figures  of  the  number  are  37,043.  The  charac- 
teristic being  3,  the  number  is  3,704.3.     Ans. 

Example. — Find  the  number  w^hose  logarithm  is  5.95424. 

Solution. — The  mantissa  is  found  in  the  column  headed  0, 
opposite  900  in  the  column  headed  N.  Hence,  the  fourth 
figure  is  0,  and  the  number  is  900,000,  the  characteristic 
being  5.  Had -the  logarithm  been  5.95424,  the  number  would 
have  been  .00009.     Ans. 

Example. — Find  the  number  whose  logarithm  is  .93036. 

Solution. — The  first  three  figures  of  the  mantissa,  930,  are 
found  in  the  0  column,  opposite  852  in  the  N  column;  but 
since  the  last  two  figures  of  all  the  mantissas  in  this  row  are 
greater  than  36,  we  must  seek  the  next  less  mantissa  in  the 
preceding  row.  We  find  it  to  be  93,034  (the  star  directing  us 
to  use  93  instead  of  92  for  the  first  two  figures),  in  the 
column  headed  8.  The  difference  for  this  .case  is  039  —  034 
=  5,  and  the  P.  P.  is  036-034  =  2.  Looking  in  the  P.  P. 
section  for  the  column  headed  5,  we  find  the  P.  P.,  2,  opposite 
4.  Hence,  the  fifth  figure  is  4;  the  fourth  figure  is  8;  the 
first  three  figures  851 ,  and  the  number  is  8.5184,  the  character- 
istic being  0.     Ans. 

Example. — Find  the  number  whose  logarithm  is  2.05753. 

Solution. — The  next  less  mantissa  is  found  in  column 
headed  1,  opposite  114  in  the  N  column;  hence,  the  first 
four  figures  are  1,141.  The  difference  for  this  case  is  767  —  729 
=  38.  and  the  P.  P.  is  753-729  =  24.  Looking  in  the  P.  P. 
section  for  the  column  headed  38,  we  find  that  24  falls  between 
22.8  and  26.6.     The  difference  between  24  and  22.8  is  1.2. 


36  LOGARITHMS 

and  between  24  and  26.6  is  2.6;  hence,  24  is  nearer  22.8  than 
it  is  to  26.6,  and  6,  opposite  22.8,  is  the  fifth  figure^ of  the 
number.  Hence,  the  number  whose  logarithm  is  2.05753 
is  .011416.     Ans. 

In  order  to  calculate  by  means  of  logarithms,  a  table  is 
absolutely  necessary.  Hence,  for  this  reason,  we  do  not 
explain  the  method  of  calculating  a  logarithm.  The  work 
involved  in  calculating  even  a  single  logarithm  is  very  great, 
and  no  method  has  yet  been  demonstrated,  of  which  we  are 
aware,  by  which  the  logarithm  of  a  number  like  121  can  be 
calculated  directly.  Moreover,  even  if  the  logarithm  could 
be  readily  obtained,  it  would  be  useless  without  a  complete 
table,  such  as  that  which  is  here  given,  for  the  reason  that 
after  having  used  it,  say  to  extract  a  root,  the  number  cor- 
responding to  the  logarithm  of  the  result  could  not  be  found. 

MULTIPLICATION  BY  LOGARITHMS 

The  principle  upon  which  the  process  is  based  may  be 
illustrated  as  follows :  Let  X  and  Y  represent  two  numbers 
whose  logarithms  are  x  and  y.  To  find  the  logarithm  of 
their  product,  we  have,  from  the  definition  of  a  logarithm, 

10'   =X         (1) 
and  10^   =Y         (2) 

Since  both  members  of  (1)  may  be  multiplied  by  the  same 
quantity  without  destroying  the  equality,  they  evidently 
may  be  multiplied  by  equal  quantities  like  10^'  and  y. 
Hence,  multiplying  (1)  by  (2),  member  by  member, 

10'  X  lO''  =  10*+"  =  XY 
or,  by  the  definition  of  a  logarithm,  x  +  y  =  \og  X  Y.  But 
A'  Y  is  the  product  of  X  and  Y,  and  x  +  y  \s  the  sum  of  their 
logarithms;  from  which  it  follows  that  the  sum  of  the  loga- 
rithms of  two  numbers  is  equal  to  the  logarithm  of  their 
product.     Hence, 

To  multiply  two  or  more  numbers  by  using  logarithms: 

Rule. — Add  the  logarithms  of  the  several  numbers,  and  the 
sum  will  be  the  logarithm  of  the  product.  Find  the  number 
corresponding  to  this  logarithm,  and  the  result  will  be  the  num- 
ber sought. 


LOGARITHMS  37 

Example.— MvlWav^Y  4.38,  5.217,  and  83  together. 
Solution.—     Log   4.38    =     .64147 

Log  5.217  =     .71742 

Log       83  =  1.91908 

Adding,  3.27797  =  log  (4.38X5.217X83) 

Number  corresponding  to  3.27797  =  1,896.6.  Hence,  4.38 
X  5.217X83  =  1,896.6,  nearly.     Ans. 

By  actual  multiplication,  the  product  is  1,896.5818, 
showing  that  the  result  obtained  by  using  logarithms  was 
correct  to  five  figures. 

When  adding  logarithms,  their,  algebraic  sum  is  always 
to  be  found.  Hence,  if  some  of  their  numbers  multiplied 
together  are  wholly  decimal,  the  algebraic  sum  of  the  char- 
acteristics will  be  the  characteristic  of  the  product.  It  must 
be  remembered  that  the  mantissas  are  always  positive. 

Example.— UyAtiply  49.82,  .00243,  17,  and  .97  together. 

Solution. — 

Log  49.82  =  1.69740 
Log  .00243  =  3.38561 
Log  17  =  1.23045 
Log  .97  =  1.98677 
Adding,  0.30023  =  log  (49.82X  .00243X17X.97) 

Number  corresponding  to  0.30023  =  1.9963.  Hence,  49.82 
X. 00243  X  17  X. 97  =  1.9963.     Ans. 

In  this  case  the  sum  of  the  mantissas  was  2.30023.  The 
integral  2  added  to  the  positive  characteristics  makes  their 
sum=^  +  l  +  l=4;  sum  of  negative  characteristics  =  3 
+1=4,  whence  4+(-4)=0.  If,  instead  of  17,  the  number 
had  been  .17  in  the  above  example,  the  logarithm  of  .17 
would  have  been  1^23045,  and  the  sum  of  the  logarithms 
would  have  been  2.30023;  the  product  would  then  have 
been  .019963; 

It  can  now  be  shown  why  all  numbers  with  figures  in  the 
same  order  have  the  same  mantissa,  without  regard  to  the 
decimal  point.  Thus,  suppose  it  were  known  that  log  2.06 
=  .31387.  Then,  log  20.6  =  log  (2.06X10)  =  log  2.06  + log  10 
=  .31387  +  1  =  1.31387.  And  so  it  might  be  proved  with  the 
decimal  point  in  any  other  position. 


38  LOGARITHMS 

DIVISION  BY  LOGARITHMS 

As  before,  let  A'  and  Y  represent  two  numbers  whose 
logarithms  are  x  and  y.  To  find  the  logarithm  of  their 
quotient,  we  have,  from  the  definition  of  a  logarithm: 

10"   =   A'     (1) 
and  10^   =    y     (2) 

Dividing  (1)  by  (2),  lO"""^  =  ^>  or,  by  the  definition  of  a 

Y  X 

logarithm,;*;  — y  =  log  'y.    But  y  is  the  quotient  of  X  -^  Y, 

and  x  —  y  vs.  the  difference  of  their  logarithms,  from  which  it 
follows  that  the  difference  between  the  logarithms  of  two 
numbers  is  equal  to  the  logarithm  of  their  quotient.  Hence, 
to  divide  one  number  by  another  by  means  of  logarithms: 

Rule. — Subtract  the  logarithm  of  the  divisor  from  the  logarithm 
of  the  dividend,  and  the  result  will  be  the  logarithm  of  the 
quotient. 

Example.— Divide  6,784.2  by  27.42. 

Solution.—    Log  6,784.2   =  3.83150 
Log      27.42   =   1.43807 

difference  =  2.39343  =  log  (6,784.2-^27.42) 

Number  corresponding  to  2.39343  =  247.42.  Hence, 
6,784.2-^-27.42  =  247.42. 

When  subtracting  logarithms,  their  algebraic  difference  is 
to  be  found.  The  operation  may  sometimes  be  confusing, 
because  the  mantissa  is  always  positive,  and  the  character- 
istic may  be  either  positive  or  negative.  When  the  logarithm 
to  be  subtracted  is  greater  than  the  logarithm  from  which  it  is  to 
be  taken,  or  when  negative  characteristics  appear,  subtract  the 
mantissa  first,  and  then  the  characteristic,  by  changing  its  sign 
and  adding. 

Example.— Divide  274.2  by  6,784.2. 

Solution.—     Log     274.2  =  2.43807 

Log  6.784.2  =  3.83150 

2.60657 

First  subtracting  the  mantissa  .83150  gives  .60657  for  the 
mantissa  of  the  quotient.  In  subtracting,  1  had  to  be  taken 
from  the  characteristic  of  the  minuend,  leaving  a  charac- 
teristic of  1.      Subtract  the  characteristic  3  from  this,  by 


LOGARITHMS  39 

changing  its  sign  and  adding  1  —  3  =  2,  the  characteristic  of 
the  quotient.  Number  corresponding  to  2. 60657  =  .040418. 
Hence,  274.2 -i- 6,784.2  =  .040418.     Ans. 

Example.— Divide  .067842  by  .002742. 

Solution.—     Log  .067842  =  2.83150 
Log  .002742  =  3.43807 

difference  =  1.39343 

Since  .83 1 50  -  .43807  =  .39343  and  -2  +  3  =  1,  number  cor- 
responding to  1.39343=24.742.  Hence,  .067842 h- .002742 
=  24.742.     Ans. 

The  only  case  that  is  likely  to  cause  trouble  in  subtract- 
ing is  that  in  which  the  logarithm  of  the  minuend  has  a 
negative  characteristic,  or  none  at  all,  and  a  mantissa  less 
than  the  mantissa  of  the  subtrahend.  For  example,  let  it 
be  required  to  subtract  the  logarithm  3.74036  from  the 
logarithm  3.55145.  The  logarithm  3.55145  is  equivalent  to 
—  3 +  .55145.  Now,  if  we  add  both  +1  and  —1  to  this 
logarithm,  it  will  not  change  its  value.  Hence,  3.55145 
=  -3 -1  +  1 +.55145  =  4+ 1.55145.  Therefore,  3.55145 
-3.74036  = 

4  +  1.55145 
3+   .74036 


difference  =  7+   .81109  =  7.81109 
Had  the   characteristic   of  the   above   logarithm   been  0 
instead  of  3,  the  process  would  have  been  exactly  the  same. 
Thus,  .55145=1  +  1.55145;  hence, 
1  + 1.55145 
3+    .74036 


difference  =  4+  .81109  =  4.81109 
^   Example.— mvide  .02742  by  67.842.  _ 
Solution.—     Log  .02742=2.43807=3  +  1.43807 
Log  67.842  =  1.83150=1+   .83150 

difference  =  4+  .60657  =  4.60657 
Number    corresponding    to  4.60657  =  .00040417.      Hence, 
.02742 -H  67.842  =  .00040417.     Ans. 

Example. — What  is  the  reciprocal  of  3.1416? 


40  LOGARITHMS 

Solution. — Reciprocal   of  3.1416=     -.^■■o.  and  log  oTITfi 
=  log  1 -log  3.1416  =  0- .49715.     Since  0=  -1  +  1, 
1  +  1.00000 
.49715 

difference  =  T+    .50285  =  T.50285 
Number  whose  logarithm  is   1.50285  =  .31831.     Ans. 

INVOLUTION  BY  LOGARITHMS 

If  A'  represents  a  number  whose  logarithm  is  x,  we  have, 
from  the  definition  of  a  logarithm, 
10"^  =  X 

Raising  both  numbers  to  some  power,  as  the  nth,  the 
equation  becomes  10"^'"  =  A" 

But  A"  is  the  required  power  of  A,  and  xn  is  its  logarithm, 
from  which  it  follows  that  the  logarithm  of  a  number  mul- 
tiplied by  the  exponent  of  the  power  to  which  it  is  raised  is 
equal  to  the  logarithm  of  the  power.  Hence,  to  raise  a 
number  to  any  power  by  the  use  of  logarithms: 

Rule. — Multiply  the  logarithm  of  the  number  by  the  exponent 
that  denotes  the  power  to  which  the  number  is  to  be  raised,  and 
the  result  will  be  the  logarithm  of  the  required  power. 

Example.— 'Whsit  is:  (a)  the  square  of  7.92?  (6)  the  cube 
of  94.7?     (c)  the  1.6  power  of  512,  that  is,  the  value  of  5121-6? 

Solution.— {a)  Log  7.92  =  .89873;  exponent  of  power  =  2. 
Hence,  .89873  X2  =  1.79746  =  log  7.922.  Number  correspond- 
ing to  1.79746  =  62.727.     Hence,  7.922  =  62.727,  nearly.    Ans. 

(b)  Log  94.7  =  1.97635;  1.97635X3  =  5.92905  =  log  94.73. 
Number  corresponding  to  5.92905  =  849,280,  nearly.  Hence, 
94.73  =  849.280,  nearly.     Ans. 

(c)  Log  512i-6  =  1.6Xlog  512  =  1.6X2.70927=  4.334832 
or  4.33483  (when  using  five-place  logarithms)  =  log  21,619. 
Hence,  5121-6  =  21,619,  nearly.     Ans. 

If  the  number  is  wholly  decimal,  so  that  the  characteristic 
is  negative,  multiply  the  two  parts  of  the  logarithm  separately  by 
the  exponent  of  the  number.  If,  after  multiplying  the  mantissa, 
the  product  has  a  characteristic,  add  it,  algebraically,  to  the 
negative  characteristic  multiplied  by  the  exponent,  and  the 
result  will  be  the  negative  characteristic  of  the  required  power. 


LOGARITHMS  41 

Example. — Raise  .0751  to  the  fourth  power. 

Solution.— Log  .0751^  =  4  X log  .0751  =4  X  2.87564.  Multi- 
plying the  parts  separately,  4X2  =  8  and  4  X  .87564  =  3.50256. 
Adding  the  3  and  8,  3  + (-8)=  -5;  therefore,  log  .0751* 
=  5.50256.  Number  corresponding  to  this  =  .00003181. 
Hence,  .0751*  =  . 00003181.     Ans. 

A  decimal  may  be  raised  to  a  power  whose  exponent  con- 
tains a  decimal  as  follows: 

Example. — Raise  .8  to  the  1.21  power. 

Solution.— Log  .8'-2i  =  1.21  X  1.90309.  There  are  several 
ways  of  performing  the  multiplication. 

First  Method. — Adding  the  characteristic  and  mantissa 
algebraically,  the  result  is  —.09691.  Multiplying  this  by 
1.21  gives  —.1172611,  or  —.11726,  when  using  five-place 
logarithms.  To  obtain  a  positive  mantiss^,  add  +1  and 
-1;  whence,  log  .8i-2i=    -1  +  1 -.11726=  1.88274.     Ans. 

Second  Method. — Multiplying  the  characteristic  and  man- 
tissa separately  gives  —1.21  +  1.09274.  Adding  character- 
istic and  mantissa  algebraically,  gives  —.11726;  then,  adding 
+  1  and  -1.  log  .81-21  =  1.88274.     Ans. 

Third  Method. — Multiplying  the  characteristic  and  man- 
tissa separately  gives  —1.21  +  1.09274.  Adding  the  decimal 
part  of  the  characteristic  to  the  mantissa  gives  —  1  +  ( —  .21 
+  1.09274)  =  7.88274  =  log  .8i-2i.  The  number  corresponding 
to  the  logarithm  1.88274  =  .76338.     Ans. 

Any  one  of  the  above  three  methods  may  be  used,  but  we 
recommend  the  first  or  the  third.  The  third  is  the  most 
elegant  and  saves  figures,  but  requires  the  exercise  of  more 
caution  than  the  first  method  does.  Below  will  be  found  the 
entire  work  of  multiplication  for  both_^8i-2i  and  .8-21. 
1.90309  1.90309 

1.21 ^ 

90309  90309 

180618  180618 

^Q^*^  +1.1896489 


1.0927389  -1-.21 

1.21 


1.9796489,  or  1.97965 


1.8827389,  or  1.88274 


42  LOGARITHMS 

In  the  second  case,  the  negative  decimal  obtained  by 
multiplying  —  1  and  .21  was  greater  than  the  positive  decimal 
obtained  by  multiplying  .90309  and  .21;  hence,  +1  and  —1 
were  added,  as  shown. 

EVOLUTION  BY  LOGARITHMS 

If  X  represents  a  number  whose  logarithm  is  x,  we  have, 

from  the  definition  oS  a  logarithm, 

10'  =  X 

Extracting  some  root  of  both  members,  as  the  nth,  the 

eq,uation  becomes 

I 

10'^=  '-v'X 

But  ^pC  is  the  required  root  of  X,  and  -  is  its  logarithm, 

from  which  it  follows  that  the  logarithm  of  a  number  divided 
by  the  index  of  the  root  to  be  extracted  is  equal  to  the 
logarithm  of  the  root.  Hence,  to  extract  any  root  of  a  num- 
ber by  means  of  logarithms: 

Rule. — Divide  the  logarithm  of  the  number  by  the  index  of 
the  root;  the  result  will  be  the  logarithm  of  the  root. 

Example. — Extract  (o)  the  square  root  of  77,851;  (b)  the 
cube  root  of  698,970;  (c)  the  2.4  root  of  8  964,300. 

Solution.— (a)  Log  77,851=4.89127;  the  index  of  the 
root  is  2;  hence,  log  >/77,851  =4.89127^2=2.44564;  number 
corresponding  to  this  =  279.02.  Hence,  "^77^1  =  279.02, 
nearly.     Ans. 

(b)  Log  -^698,970  =  5.84446 -^3  =  1.94815  =  log  88.746;  or 
4698,970  =  88.747,  nearly.     Ans. 

(c)  Log 'v^8,964,3'00  =  6.95251 -i-2.4  =  2.89688  =  log 788.64; 
or.  '■i'/8.964,300  =  788.64,  nearly.     Ans. 

If  it  is  required  to  extract  a  root  of  any  number  wholly 
decimal,  and  the  negative  characteristic  will  not  exactly 
contain  the  index  of  the  root,  without  a  remainder,  proceed 
as  follows: 

Separate  the  two  parts  of  the  logarithm;  add  as  many  units 
(or  parts  of  a  unit)  to  the  negative  characteristic  as  will  make 


LOGARITHMS  43 

*/  exactly  ^contain  the  index  of  the  root.     Add  the  same  number 

to   the  mantissa,   and  divide  both   parts  by  the   index.     The 

result  will  be  the  characteristic  and  mantissa  of  the  root. 

Example. — Extract  the  cube  root  of  .0003181. 

c  7   .-  T       ^   nnnQioi       log  .0003181      4.50256 

Solution. — LogF  .0003181  =— ^ — ~ = — 

o  o 

(4 +  2  =  6) +  (2 +  .50256  =  2. 50256) 

(6  -h  3  =  2) +  (2.50256  h-  3  =  .83419) 

or.  logf  .OOO3T8I  =2.83419  =  log  .068263 

Hence.  t^  .0003181  =  .068263.     Ans. 

Example.— Vmd.  the  value  of  ^"v^. 0003181. 

c  7  ,•          T       i-V/TiT^oT^     log  .0003181     4.50256 
Solution.— L,os      y  .0003181  =  =  . 

If  —.23  be  added  to  the  characteristic,  it  will  contain  1.41 
exactly  3  times.     Hence, 

[  -  4  +  ( -  .23)  =  -  4.23]  +  (.23  +  .50256  =  .73256) 
(-4.23 -5- 1.41  =3)  + (.73256^-1.41  =  . 51955) 
or,  log  '■  v^.0003181  =3.51955  =  log  .0033079 

Hence,  '"y^. 0003181  =  .0033079.     Ans. 

Example. — Solve  this  expression  by  logarithms: 
497  X  .0181X762  _ 
3.300  X. 651 7 

Solution. —      Log  497  =  2.69636 

Log        .0181=2.25768 
Log  762=2.88195 


Log  product  =  3.83599 
Log  3,300  =  3.51851 
Log       .6517  =  1.81405 


Log  product  =  3.33256 
3.83599 -3.33256  =  . 50343  =  log  3.1874 
„  497  X  .0181X762        .  ^  __ .        . 

"'"^^'  3,300  X. 6517      =3.1874.     Ans. 


Example. —Solve-^    504.203X507   ^     logarithms. 
\1. 75X71.4X87 


44  LOGARITHMS 

Soiunon.—      Log  504,203  =  5.70260 

Log  507  =  2.70501 

Log  product  =  8.40761 

Log  1.75=    .24304 

Log         71.4  =  1.85370 

Log  87  =  1.93952 

Log  product  =  4.03626 

8.40761-4.03626        ,   ,.^,^     ,       oo  «k 
— =  1.45/ 12  =  log  28.65 


TT  3/504.203X507  90  ^.^       »„, 

Hence,  -\      „    '    ^ — :; — ;r=  =  28. bo.     Ans. 

\  1.75X71.4X87 

Logarithms    can    often    be    applied    to    the    solution    of 
equations. 

Example. — Solve  the  equation  2.43%^  =   -^.0648. 
Solution.—  2.43a;5  =  -^X)648 

Dividing  by  2.43,  x^  =  -^^— 

Taking  the  logarithms  of  both  numbers, 

5Xlog.  =  ^-^-^«-  log  2.43 

or  5  log  x  =  ^^^^-.38561 

D 

=  1.80193 -.38561 

=  1.41632 

Dividing  by  5,  log  x  =  1.88326; 

whence,  x  =    .7643 

Example. — Solve  the  equation  4.5^  =  8. 

Solution. — Taking  the  logarithms  of  both  numbers, 

X  log  4.5  =  log  8, 

log  8         .90309 

whence,  x  =  z -r-z  =  -£.-001' 

log  4.5        .65321 

Taking  logarithms  again,  _  _ 

log  X  =  log  .90309 -log  .65321  =  1.95573-1.81505 

=   .14068;  whence,  x  =  1.3825 

Remarks. — Logarithms    are    particularly  useful    in  those 

cases  when  the  unknown    quantity  is  an  exponent,   as  in 

the  last  example,  or  when  the  exponent  contains  a  decimal, 

as  in  several  instances  in  the  examples  given  on  pages  40-44. 


LOGARITHMS  45 

Such  examples  can  be  solved  without  the  use  of  logarithms, 
but  the  process  is  very  long  and  somewhat  involved,  and 
the  arithmetical  work  required  is  enormous.  To  solve  the 
example  last  given  without  using  the  logarithmic  table  and 
obtain  the  value  of  x  correct  to  five  figures  would  require, 
perhaps.  100  times  as  many  figures  as  were  used  in  the 
solution  given,  and  the  resulting  liability  to  error  would  be 
correspondingly  increased;  indeed,  to  confine  the  work  to 
this  number  of  figures  would  also  require  a  good  knowledge 
of  short-cut  methods  in  multiplication  and  division,  and 
judgment  and  skill  on  the  part  of  the  calculator  that  can  only 
be  acquired  by  practice  and  experience. 

Formulas  containing  quantities  affected  with  decimal 
exponents  are  generally  of  an  empirical  nature;  that  is, 
the  constants  or  exponents  or  both  are  given  such  values 
as  will  make  the  results  obtained  by  the  formulas  agree 
with  those  obtained  by  experiment.  Such  formulas  occur 
frequently  in  works  treating  on  thermodynamics,  strength 
of  materials,  machine  design,  etc. 


46 


LOGARITHMS 


COMMON    LOGARITHMS. 


N.    L.  0    1 


100 

101 
102 


3      4 


P.  P. 


104 
105 
106 
10 
108 
1 

no 

111 

112 
113 
114 
115 
116 
117 
118 
119 

120 

121 

122 
123 
124 
125 
126 
12' 
128 
129 

130 

131 
132 
133 
134 
135 
136 
137 
138 
139 

140 

141 
142 
143 
144 
145 
146 
147 
148 
149 


00  000 
432 
860 

01  284 
03 

02  119 
531 
938 

03  342 
743 

04  139 
532 
922 

05  308 
690 

06  070 
446 
819 

07 
555 


217 


561  604 
*030 


729 
108 
483 
856 
225 
591 


08  279 
636 
991 

09  342 
691 

10  037 
380 
721 

11  059 
394 
727 

12  057 
385 
710 

13  033 
354 
672 
988 

14  301 
613 
922 

15  229 
534 
836 

16  137 
435 
732 

17  026 
319 
609 


954 
314 

672 
*026 
377 
726 
072 
415 
755 
093 
428 

~76o; 

090 
418 
743 
066 
386 
704 
#019 
333 1 
~644 
^953 
259 
564 
866 
167 
465 
761 
056 
348 


N.  L.  0  1   2   3   4   5   6   7 


260  303 

32 
«115|*157 

I  578 


9531  995  *036 
3661  407  449 
7761  816  857 
*181  *222  *262 
5831  6231  663 
981  *021  »060 


346  389 
"775 
#1991*242 

620 I  662 

*078 


376  415 
~766l~805 
*154  *192 

538 

918 

296 


454 

"844 

*231 

576 

956  994 
333:  371 
707!  744 
078  *115 
445!  482 
809  846 


*171 1*207 


529 

884 
*237i 
587 
934 
278! 
6191 
9241  9581 
261 1  294 
594|~628 


926 
254 
581 
905 
226 
545 
862 
*176 
489  520 
799 


959  992 
287 1  320 
6131  646 
9371  969 
258!  290 
577 

925 
#239 

551 


44 

43 

4.4 

4.3 

8.8 

8.6 

13.2 

12.9 

17.6 

17.2 

22.0 

21.5 

26.4 

25.8 

30.8 

30.1 

35.2 

34  4 

39.6 

38.7  1 

4i 

40 

4.1 

4.0 

8.2 

fi.O 

12.3 

12.0 

16.4 

16.0 

20.5 

20.0 

24.6 

24.0 

28.7 

28.0 

32.8 

32.0 

36.9 

36.0 

38 

37 

3.S 

3.7 

7.6 

7.4 

11.4 

11.1 

15.2 

14.8 

19.0 

18.5 

22.8 

22.2 

26.6 

25.9 

30,4 

29  6 

34.2 

33.3 

35 

34 

3.5 

3.4 

7.0 

6.8 

10.5 

10.2 

14.0 

13.6 

17.5 

17.0 

21.0 

20.4 

24.5 

23.8 

2K.0 

27.2 

31.5 

30.6 

32 

31 

3.2 

3.1 

6.4 

6.2 

9.6 

9.3 

12.8 

12.4 

16.0 

15.5 

19.2 

18.6 

22.4 

21.7 

25.6 

24.8 

28.8 

27.9 

P.  p. 


LOGARITHMS 


47 


Table— 

( Continued) 

N. 

L.  0 

1 

!_ 

3 

4 

5 

6 

7 

8 

9 

P.P. 

ISO 

17  609 

"638 

667 

"696 

"725 

l54 

^82 

^TT 

"840 

l69 

151 

898 

926 

955 

984 

»013 

*041 

»070 

»099 

»127 

il56 

29   28 

152 

18  184 

213 

241 

270 

298 

327 

355 

384 

412 

441 

1 

2.9 

2.8 

153 

469 

498 

526 

554 

583 

611 

639 

667 

696 1  724 

2 

5.8 

5.6 

154 

752 

7«0 

808 

837 

865 

893 

921 

949 

977,*005 

3 

8.7 

8.4 

155 

19  033 

061 

0»9 

117 

145 

173 

201 

229 

257 

285 

4 

11.6 

11.2 

156 

312 

340 

368 

396 

424 

451 

479 

507 

535 

562 

5 

14.5 

U.O 

157 

590 

618 

645 

673 

700 

728 

756 

783 

811 

838 

6 

17.4 

16.8 

158 

866 

893 

921 

948 

976 

*003 

*030 

*058 

*085 

*112 

7 

20.3 

19.6 

159 

20  140 

167 

194 

222 

249 

276 

303 

330 

358 

385 

8 

23.2 

22.4 

160 

412 

^439 

466 

193 

"520 

"548 

"575 

602 

629 '"656 

9 

26.1 

25.2 

161 

683 

^no 

737 

"763 

790 

817 

844 

871 

898  925 

27   26 

162 

952 

978 

«005 

«032 

»059 

*085 

*n2 

*139 

*165  #192 

1 

2.7 

2.6 

163 

21  219 

245 

272 

299 

325 

352 

378 

405 

431'  458 

2 

5.4 

5.2 

164 

484 

511 

537 

564 

590 

617 

643 

669 

696'  722 

3 

8.1 

7.8 

165 

748 

775 

801 

827 

854 

906 

932 

958;  985 

4 

10.8 

10.4 

166 

22  Oil 

037 

063 

089 

115 

141 

167 

194 

220 i  246 

5 

13.5 

13.0 

167 

272 

298 

324 

350 

376 

401 

427 

453 

479  505 

6 

16.2 

15.6 

168 

531 

557 

583 

608 

634 

660 

686 

712 

737!  763 

7 

18.9 

18.2 

169 

789 

814 

840 

866 

891 

917 

943 

968 

994  '!019 

8 

21.6 

20.8 

170 

23  045 

"OTO 

^096 

"m 

147 

l72 

198 

-Wz 

"249  "274 

9 

24.3 

23.4 

171 

300 

325 

350 

376 

"ioi 

^26 

452 

477 

5021  528 

25 

172 

553 

578 

603 

629 

654 

679 

704 

729 

754  779 

2.5 

173 

805 

830 

855 

880 

905 

930 

955 

980 

*005  *030 

5.0 

174 

24  055 

080 

105 

1-30 

155 

180 

204 

229 

254  279 

7.5 

175 

304 

329 

353 

378 

403 

428 

452 

477 

502 1  527 

10.0 

176 

551 

576 

601 

625 

650 

674 

699 

724 

748,  773 

12.5 

177 

797 

822 

846 

871 

895 

920 

944 

969 

993  »018 

15.0 

178 

25  042 

066 

091 

115 

139 

164 

188 

212 

2371  261 

17.5 

179 

285 

310 

334 

358 

382 

406 

431 

455 

479  503 

20.0 

180 

527 

551 
792 

^75 

816 

"600 
840 

"624 
864 

648 

888 

672 
912 

696 
935 

720  744 
959,  983 

22.5 

181 

768 

24   23 

182 

26  007 

031 

055 

079 

102 

126 

150 

174 

198  221 

2.4 

2.3 

183 

245 

269 

293 

316 

340 

364 

387 

411 

435  458 

4.8 

4.6 

184 

482 

505 

529 

553 

576 

600 

623 

647 

670 '  694 

7.2 

6.9 

185 

717 

741 

764 

788 

811 

834 

858 

881 

905!  928 

9.6 

9.2 

186 

951 

975 

998 

*021 

*045 

*068 

*091 

*114 

*138  »161 

12.0 

11.5 

187 

27  184 

207 

231 

254 

277 

300 

323 

346 

370  393 

14.4 

13.8 

188 

416 

439 

462 

485 

508 

531 

554 

577 

600  623 

16.8 

16.1 

189 

646 

669 

692 

715 

738 

761 

784 

807 

830  852 

19.2 
21.6 

18.4 
20.7 

190 

875 

898 

921 

944 

967 

989 

*012 

*035 

*058'*081 

191 

28  103 

126 

Ti9 

171 

194 

217 

"240 

262 

285  307 

22   21 

192 

330 

353 

375 

398 

421 

443 

466 

488 

511 

533 

2.2 

2.1 

193 

556 

578 

601 

623 

646 

668 

691 

713 

735 

758 

4.4 

4.2 

194 

780 

803 

625 

847 

870 

892 

914 

937 

959 

981 

6.6 

6.3 

195 

29  003 

026 

048 

070 

092 

115 

137 

159 

181 

203 

8.8 

8.4 

196 

226 

248 

270 

292 

314 

336 

358 

380 

403 

425 

11.0 

10.5 

197 

447 

469 

491 

513 

535 

557 

579 

601 

623 

645 

13.2 

12.6 

198 

667 

688 

710 

732 

754 

776 

798 

820 

842 

863 

15.4 

14.T 

199 

907 

929 

951 

973 

994 

*016 

»038 

»060  *081 

8 
9 

17.6 

16.8 

200 

30  103 

^5 

~T46 

168 

190 

211 

~izz 

~255 

"276 

298 

19.8  1  10.9 

N. 

L.O 

1 

2 

3 

4 

5 

6 

7 

8 

9 

P.P. 

48 


LOGARITHMS 
Table— ( Continued). 


N. 

L.O 

1 
T25 

2 
lie 

3 

l68 

4 

l90 

5 
ITT 

6 
"233 

7 

8 

± 

P.  P. 

200 

30  103 

~255  276  298 

201 

320 

T4T 

"363 

384 

406 

428 

449 

47l|  492I  514 

22 

21 

202 

535 

557 

578 

600 

621 

643 

664 

685  707 1  728 

1 

2.2 

2.1 

203 

750 

792 

814 

835 

856 

878 

899;  920  942 

2 

4.4 

4.2 

204 

963 

984 

#006 

*027 

*048 

*069 

*091 

*112,*133,*154 

3 

6.6 

6.3 

205 

31  175 

197 

218 

239 

260 

281 

302 

323  3451  366 

4 

8.8 

8.4 

206 

387 

408 

429 

450 

471 

492 

513 

5341  555  576 

5 

11.0 

10.5 

207 

597 

618 

639 

660 

681 

702 

723 

744'  7651  785 

6 

13.2 

12.6 

208 

80B 

827 

848 

869 

890 

911 

931 

952  9731  994 

7 

15.4 

14.7 

209 

32  015 

035 

056 

077 

098 

118 

139 

160  181  201 

8 

17.6 

16.8 

210 

222 

243 

263 

"284 

l05 

325 

346 

366!  387  408 

9 

19.8 

18.9 

211 

428 

"449 

l69 

490 

510 

531 

552 

572  593  613 

20 

212 

634 

654 

675 

695 

715 

736 

756 

777 1  797  818 

1 

2.0 

213 

838 

858 

879 

899 

919 

940 

960 

980  *001  »021 

2 

4.0 

214 

33  041 

062 

082 

102 

122 

143 

163 

183'  2031  224 

3 

6.0 

215 

244 

264 

284 

304 

325 

345 

365 

385  405!  425 

4 

8.0 

216 

445 

465 

486 

506 

526 

546 

566 

586 i  6061  626 

5 

10.0 

217 

646 

666 

686 

706 

726 

746 

766 

786'  8061  826 

6 

12.0 

218 

846 

866 

885 

905 

925 

945 

965 

9851*005  *025 

7 

14.0 

219 

34  044 

064 

084 

104 

124 

143 

163 

183,  203}  223 

8 

16.0 

220 

242 

"262 

282 

^01 

~321 

141 

"361 

"380 

400  420 

9 

18.0 

221 

~"439 

459 

~4iy 

498 

"518 

537 

"557 

577 

"596-616 

19 

222 

635 

655 

674 

694 

713 

733 

g 

772 

7921  811 

1 

1.9 

223 

830 

850 

869 

889 

908 

928 

967 

9861*005 

2 

3.8 

224 

35  025 

044 

064 

083 

102 

122 

141 

1601  I8OI  199 

3 

5.7 

225 

218 

238 

257 

276 

295 

315 

334 

353:  372 

392 

4 

7.6 

226 

411 

430 

449 

468 

488 

507 

526 

545  564 

583 

5 

9.5 

227 

603 

622 

641 

660 

679 

698 

717 

736 1  755 

774 

6 

11.4 

228 

793 

813 

832 

851 

870 

908 

927  946 

965 

7 

13.3 

229 

984 

*003 

*021 

*040 

*059 

»078 

*097 

*116!*135 

*154 

8 

15.2 

230 

36  173 

192 

211 

229 

248 

267 

286 

305  324 

342 

9 

17.1 

231 

361 

-380 

399 

418 

436 

I55 

-474 

493:  511 

530 

18 

232 

549 

568 

586 

605 

624 

642 

661 

680 1  .698 

717 

1 

1.8 

233 

736 

754 

773 

791 

810 

829 

847 

866 

884 

903 

2 

3.6 

234 

922 

940 

959 

977 

996 

*014 

*033 

*051 

*070 

*088 

3 

5.4 

235 

37  107 

125 

144 

162 

181 

199 

218 

236 

254 

273 

4 

7.2 

236 

291 

310 

328 

346 

365 

383 

401 

420 

438 

457 

5 

9.0 

237 

475 

493 

511 

530 

548 

566 

585 

603 

621 

639 

6 

10.8 

238 

658 

676 

694 

712 

731 

749 

767 

785 

803 

822 

7 

12.6 

239 

840 

858 

876 

894 

912 

931 

949 

967!  985 

*003 

8 

14.4 

240 

38  021 

039 

"057 

075 

"093 

T12 

^130 

l48 

-166 

184 

9 

16.2 

241 

202 

^220 

238 

~256 

"274 

"292 

310 

328 

^6 

364 

17 

242 

882 

399 

417 

435 

453 

471 

489 

507 

525 

543 

1 

1.7 

243 

561 

578 

596 

614 

632 

650 

668 

686 

703 

721 

2 

3.4 

244 

739 

757 

775 

792 

810 

828 

846 

863 

881 

3 

5.1 

245 

917 

934 

952 

970 

987 

»005 

*023 

*041 

*058 

*076 

4 

6.8 

246 

3»094 

111 

129 

146 

164 

182 

199 

217 

235 

252 

6 

8.5 

247 

270 

287 

305 

322 

340 

358 

375 

393 

410 

428 

6 

10.2 

248 

445 

463 

480 

498 

515 

533 

550 

568 

585 

602 

7 

11.9 

249 

620 

637 

655 

672 

690 

707 

724 

742 

759  777 

8 

13.6 

2S0 

794 

811 

829 

l46 

863 

881 

898 

915 

933 

950 

9 

15.3 

N. 

L.O 

1 

2 

3 

4 

5 

6 

7 

8 

9 

P.  P. 

LOGARITHMS 
Table— ( Continued). 


49 


N. 

L.0 

1   2 

3   4 

5   6   7  1  8   9 

P.P. 

250 

39  794 

"§11  "829 

"846  "863 

"881  "898  "915  "933  "950 

251 

967 

~985  »062 

*m9  "(m 

*054:»071i*088  »T06  »T23 

18 

252 

40  HO 

157!  175 

192]  209 

226  243!  261:  278  295 

1.8 

253 

312 

329 1  346 

364'  381 

398 1  415 1  432  449  466 

3.6 

254 

483 

500  518 

535 1  552 

569 1  586  603;  620  637 

5.4 

255 

654 

671  688 

705!  722 

7391  756 1  773,  790  807 

7.2 

256 

824 

841  858 

875  892 

909:  926  943  960  976 

9.0 

257 

993 

*010  *027 

*044  #061 

*078l*095!*lll  #128  *145 

10.3 

258 

41  162 

179!  196 

2121  229 

2461  2631  280  296  313 

12.6 

259 

330 

347  363 

380 j  397 

414 1  430  447  464  481 

14.4 

16.3 

260 

497 

514;  531 

547)  564 

"5811 "597 |~614  "631  "647 

I7_ 

261 

664 

"681^697 

714|  731 

747 1  764  j  780  797  814 

262 

830 

847  863 

880  896 

913  929  946  963  979 

1.7 

263 

996 

»012  »029  »045  *062 

*o-8  *095  nn  nil  nn 

3.4 

264 

42  160 

177,  193 

210  226 

243  259  275  292  308 

5.1 

265 

325 

341  357 

3741  390 

4061  423  439  455  472 

6.3 

266 

488 

504  521 

537  553 

570  i  586  602  619  635 

8.5 

267 

651 

607 1  684 

700i  716 

732 1  7491  765  781  797 

10.3 

268 

813 

830 !  846 

862  878 

8941  911 1  927  943  959 

11.9 

269 

975 

991*008 

*024 1*040 

#056  >072  *088  »104  »120 

13.6 
15.3 

270 

43  136 

152 i  169 

ItejloT 

"2T7:"233  "249,^65  "281 

271 

297 

313,  329 

345 

361 

377.  393,  409  425  441 

16 

272 

457 

473  489 

505 

521 

537 1  553,  569  584  600 

1.6 

273 

616 

632,  648 

664 

680 

696,  7121  727  743  759 

3.3 

274 

775 

791  807 

823 

838 

854  870  886  902  917 

4.8 

275 

933 

649  965 

981 

996 

*012  *028:*044  *059  #075 

6.4 

376 

44  091 

1071  122 

138 

154 

170,  1851  201  217  232 

8.0 

277 

248 

264  279 

295 

311 

326  342  358  373  389 

9.6 

278 

404 

420 j  436 

451 

467 

483i  498|  514  529  545 

11.3 

279 

560 

576;  5»2 

607 

623 

638 

654!  669  685  700 

8 
9 

12.3 
14.4 

280 

716 

"731  "747 

"762 

778 

"793 

809i"824  "840  "§55 

281 

871 

"886  "902 

"917 

"932 

"948 

"063i~979  "994  #010 

'5  J 

282 

45  025 

040  056 

0711  086 

102 

117  133  148  163 

1.5 

283 

179 

194  209 

225  240 

255 

271 '  286  301'  317 

3.0 

284 

332 

347,  362 

378 1  393 

408 

423  439  454  469 

4.5 

285 

484 

500  515 

530!  545 

561 

576  591  606  621 

6.0 

286 

637 

652  667 

6821  697 

712 

728,  743  758  773 

7.5 

287 

788 

803  818 

834 1  849 

864 

879  894  909  924 

9.0 

288 

939 

954  969 

984,*000 

#015 

*030,#045  #060  #075 

10.51 

289 

46  090 

105 j  120 

135 

150 

165 

I80!  195,  210  225 

12.0 
13.5 

290 

240 

255]  270 

285 

300 

315 

330,  3451  359  374 

291 

389 

404'  419 

434 

449 

464 

479'  494,  509  523 

1* 

292 

538 

553  568 

583 

598 

61 3 1  627 1  642  657 1  672 

1.4 

293 

687 

702  716 

731'  746 

761,  7761  790  805'  820 

2.8 

294 

835 

850  864 

879  894 

909  9231  938  953  967 

4.3 

295 

982 

997  *012 

*026  ■^041 

#056! #070  #085  #100  #114 

5.6 

296 

47  129 

144  159 

173  188 

202:  217  232  246  261 

7.0 

297 

276 

290,  305 

319  334 

349  363!  378  392  407 

8.4 

298 

422 

436  451 

465 1  480 

494  509!  524  538  553 

9.8 

299 

567 

582  596 

611  625 

640)  654 

669,  683,  698l 

11.2 

300 

712 

727  741 

756  770 

784  799 

813 

828'  842 

12.6 

N. 

L.O 

1   2 

3   4 

5 

6 

7 

8   9 

P.P. 

50 


LOGARITHMS 


Table— ( Continued). 


N. 

L.O 

1 

2 

±I-L 

5 

6 

7 

8 

9 

P.P. 

800 

47  712 

871 

"741 

885 

756 
900 

770 
"914 

"784 
929 

"799 
943 

"813 

958 

"828 
972 

"842 
986 

801 

857 

302 

48  001 

015 

029 

044 

058 

073 

087 

101 

116 

130 

"5. 

803 

144 

159 

173 

187 

202 

216 

230 

244 

259 

273 

304 

287 

302 

316 

330 

344 

359 

873 

387 

401 

416 

1.& 

305 

430 

444 

458 

473 

487 

501 

515 

530 

544 

558 

8.0 

306 

572 

586 

601 

615 

629 

643 

657 

671 

686 

700 

4.5 

307 

714 

728 

742 

756 

770 

785 

799 

813 

827 

841 

6.0 

308 

855 

869 

883 

897 

911 

926 

940 

954 

968 

982 

7.5 

309 

996 

»010 
150 
290 

*024 
"l64 
304 

*038 

178 
318 

*052 

"m 

332 

*066 
206 
346 

#080 
"220 
360 

#094 
234 
374 

#108 
248 
388 

#122 
262 
402 

8 
9 

9.0 
10.5 
12.0 

SIO 

49  136 

311 

276 

18.5 

812 

415 

429 

443 

457 

471 

485 

499 

513 

527 

541 

313 

554 

568 

582 

596 

610 

624 

638 

651 

665 

679 

814 

693 

707 

721 

734 

748 

762 

776 

790 

803 

817 

815 

831 

845 

859 

872 

886 

900 

914 

927 j  941 

955 

14 

816 

969 

982 

996 

#010 

#024 

#037 

#051 

#065! #079 

#092 

1.4 

317 

50  106 

120 

133 

147 

161 

174 

188 

202 

215 

229 

2.8 

318 

243 

256 

270 

284 

297 

311 

325 

338 

352 

365 

4.3 

319 

379 

393 

406 

420 

433 

447 

461 

474 

488 

501 

5.6 

529 

~542 

^56 

569 

1 
583 

"696 

"610 

"623 

"637 

7.0 

8.4 

S20 

515 

321 

651 

"664 

"678 

691 

"705 

718 

732 

745 

759 

772 

9.8 

322 

786 

799 

813 

826 

840 

853 

866 

880 

893 

907 

8 

11.2 

323 

920 

934 

947 

961 

974 

987 

#001 

#014 

#028 

#041 

9 

12.8 

324 

51  055 

068 

081 

095 

108 

121 

135 

148 

162 

175 

325 

188 

202 

215 

228 

242 

255 

268 

282 

295 

308 

326 

322 

335 

348 

362 

375 

388 

402 

415 

428 

441 

827 

455 

468 

481 

495 

508 

521 

534 

548 

561 

574 

13 

328 

587 

601 

614 

627 

640 

654 

667 

680 

693 

706 

1 

l.S 

329 

720 

733 

746 

759 

772 

786 

799 

812 

825 

838 

2 

2.6 

330 

851 

865 

878 

891 
»022 

904 
#035 

"917 

#048 

930 
^61 

943 

#075 

957 

#088 

970 
#101 

3.9 
5.2 
6.5 

831 

983 

1961*009 

832 

52  114 

127 

140 

153 

166 

179 

192 

205 

218 

231 

7^8 

333 

244 

257 

270 

284 

297 

310 

323 

336 

349 

362 

9.1 

334 

375 

388 

401 

414 

•42" 

440 

453 

466 

479 

492 

10  4 

335 

504 

517 

530 

543 

556 

569 

582 

595 

608 

621 

nil 

336 

634 

647 

660 

673 

686 

699 

711 

724 

737 

750 

337 

763 

776 

789 

802 

815 

827 

840 

853 

866 

879 

338 

892 

905 

917 

930 

943 

956 

969 

982 

994 

#007 

339 

53  020 

033 

046 

058 

071 

084 

097 

110 

122 

135 

12 

340 

148 

leijTTS 

186 

199 

212 

224 

237 

250 

263 

1.2 

841 

275 

288 

301 

314 

326 

~339 

T52 

364 

377 

390 

2.4 
3.6 
4.8 
6.0 
7.2 
8.4 
9.6 
10.8 

342 

403 

415 

428 

441 

453 

466 

479 

491 

504 

517 

843 

529 

542 

555 

567 

580 

593 

605 

618 

631 

643 

344 

656 

668 

681 

694 

706 

719 

732 

744 

757 

769 

845 

782 

794 

807 

820 

832 

845 

857 

870 

882 

895 

346 

908 

920 

933 

945 

95H 

970 

983 

995  #008 

•020 

847 

54  033 

045 

058 

070 

083 

095 

108 

120 

133 

145 

348 

158 

170 

183 

195 

208 

220 

233 

245 

258 

270 

849 

283 

295 

307 

320 

332 

345 

357 

370 

382 

394 

850 

407 

419 

432 

444 

456 

469 

481 

l94 

^06 

TTi 

N. 

L.O 

1 

2 

3 

4 

5 

6 

7 

8 

9 

P.P. 

LOGARITHMS 


51 


Table— ( Continued). 


N. 

L.O 

1   2  1  3  1  4 

5  1  6 

7|8j9 

P.P. 

350 

54  407 

~419'~432  "444  ~456 

169^81 

494;  506'  518 

351 

531^  543  555!  568  580 

593  605 

~6r7;"630  ~642 

352 

6541  667,  679  691,  704 

716!  -28 

741,  753:  765 

13 

353 

777 

790 

802'  814 1  827 

839 1  851 

864'  876'  888 

354 

900 

913 

925 

937,  949 

962  974 

986  998  »011 

1 

l.S 

855 

55  023 

035 

047 

060 i  072 

084  096 

108;  121)  133 

2 

2.6 

856 

145 

157 

169 

1821  194 

206  218 

2301  242!  255 

3 

3.9 

357 

267 

279  291 

303  315 

3281  340 

352  364  376 

4 

5.2 

358 

388 

400:  413:  425  437 

449 1  461 

4731  4851  497 

5 

6.5 

359 

509  522 j  534  546  558 

570  i  582'  594  606'  618 

6 

7 
8 

7.8 
9.1 
10.4 

360 

630 

642 1  654  666  678 

691  703;  715  727'  739 

361 

751 

763 j  7751  787  799 

811  823  835  847  859 

9 

ll.T 

362 

871 

883 i  895'  907;  919 

931  943  955  967  979 

363 

991  *003  *015  #027  *038 

*050  *062  *074  *086  *098 

364 

56  110,  122i  1341  146:  158 

170 j  182  194'  2051  217 

865 

229  2411  253!  265'  277 

289  301'  312  324'  336 

12 

366 

348'  360,  372 1  384  396 

407 

419  431  443  455 

1 

1.2 

367 

467!  478,  490,  502  514 

526 

538  549:  561 i  573 

2 

2.4- 

368 

585 i  597;  608,  620.  632 

644 

656  667,  679:  691 

3 

3.6 

369 

703|  714|  726  738.  750 

761 

773,  785  797]  808 

4 

4.8 

370 

820 

832 i  844  855  867 

879;  891  902;  914:  926 
996i'^08  »019*03l  -^43 

5 
6 
7 

6.0 
7.2 

371 

937 

949 

961  972  984 

8.4 

372 

57  054 

066 

078!  089  101 

113 

124 

136,  148]  159 

8 

9.S 

373 

171 

183 

194  206  217 

229 

241 

252 

264  276 

9 

lO.ti 

874 

287 

299 

310  322!  334 

345 

357 

368 

380  392 

375 

403 

415 

426  438  449 

461 

473 

484 

496  507 

376 

519 

530 

542  553.  565 

576 

588 

600 

611  623 

S77 

634 

646 

657 1  669  680 

692 i  7031  715 

726'  738 

II 

378 

749 

761 

772  784  795 

80-  818,  830 

841'  852 

1 

1.1 

379 

864 

875 

887!  898  910 

9211  933  944 

955'  967 

2 

2.2 

S80 

978 

"990  'KIOl  ^31^24 

^35|*047,^58  »070  «081 

3 

4 
5 
6 
7 
8 
9 

3.J 
4.4 

5.5 
6.6 

7.7 
8.3 
9.9 

381 

58  092!  104 

115i  127 

138 

T49 j  1611172, "184  I95 

382 

2061  218 

229  240 

252 

263  274  286!  297 i  309 

383 

320 

331 

343  354 

365 

377!  388!  399:  410!  422 

884 

433 

444 

456  467 

478 

490  501 i  512  524'  535 

385 

546 

557 

569  580 

591 

602 

614  625^  636  647 

386 

659 

670 

681 :  692 

704 

715 

7261  737;  749  760 

387 

771 

782  794'  805!  816 

827 

838  (  8.50  861'  872 

388 

8831  8941  906i  917:  928 

939 

950  961  973  984 

389 

995  *006 'H)17  *028  *040 

•^51  *062  *073  *084  *<)95 

10 

890 

59  106 

118'  129i  140  151 

162!  173  184  195 ^  207 

2 
3 

4 
5 
6 
7 
8 
9 

1.0 

391 

218 

229,  240:  251  262 

273 

284!  295;  306]  318 

2.0 
8.0 
4.0 
5.0 
6.0 
7.0 
8.0 
9.0 

392 

329 

340 1  351'  362  373 

384 

395 

406!  417 i  428 

393 

439 

450;  461  472  483 

494 

506 

517 

528  ^39 

894 

550 

561  572 1  5831  594 

605 

616 

627 

638  649 

895 

660 1  671!  6821  693 |  704 

715 

726 

737 

748  759 

396 

770!  780'  791  8O2!  813 

824 

835'  846 

857!  868 

397 

8791  890  901]  912^  923 

934 

945  956 

966  977 

398 

988!  999*010*021  #032 

»<)43  K154  '►065  #076  »086 

399 

60  097 

108  119,  130  141 

152  163^  173'  184]  195 
~260  "271]~282j~293J~304 

400 

206 

'2T7|~228  ~239  "249 

N. 

L.O 

1 

2   3  1  4 

~5~    6 

7   8   9 

P.P. 

52 


LOGARITHMS 


Table— ( Continued) 

N. 

L.O 

1 
"in 

2 

^28 

3   4 

"239  "249 

5   6   7 

8   9 

P.P. 

400 

60  206 

"260  "271  "282" 

"293  "304 

401 

314 

325 

3361  347  358 

369  379  390  401  412 

402 

423,  433 

4441  455 

466 

477!  487 1  498  509  520 

403 

531 1  541 

552  563 

574 

584!  595  606  617!  627 

404 

638^  649 

660!  670 

681 

692i  703!  713;  724!  735 

405 

746'  756 

767 

778 

788 

799>  810  821 !  831  842 

406 

853,  863 

874 

885  895 

906  917  927  938  949 

II 

407 

959  970 

981 

991 

*002 

*013  *023  #034  *045  *055 

408 

61  066  077 

087 

098 

109 

119  130  140  151  162 

409 

1721  183 

194 

204 

215 

2251  236  247!  257  268 

410 

278,  289 

300 

310 

321 

331  342  352  363  374 

411 

384 1  395!  405 

416 

l26 

437 1  448  458  469  479 

412 

490 1  500 

511 

521 

532 

542 1  553  563  574;  584 

413 

595  606 

616 

627 

637 

648  658  669  679  690 

8  8 

414 

700  711 

721 

731 

742 

752  763  773 1  784  794 

a 

9.9 

415 

805  815 

826 

836 

847 

857  868  878  888 >  899 

416 

909'  920 

930 

941 

951 

962  972  982  993  *003 

417 

62  014,  024 

034 

045 

055 

066  076  086  097  107 

418 

118  128 

138 

149 

159 

170  180  190  201!  211 

419 

221  232 

242 

252  263 

273  284  ^94  304  315 

420 

325  335 

~346  ^  "366 

^77  "387  "397  l08  "418 

421 

428;  439 

~449 

459 S  469 

480  490  500  511,  521 

10 

422 

531]  542 

552 

562 

572 

583  5931  603  613'  624 

1  ■  " 

l.U 

423 

634 1  644 

655 

665 

675 

685  6961  706  716  726 

2 

2.0 

424 

737:  747 

757 

767 

778 

788  798  i  808,,  818  829 

3 

425 

839 i  849 

859 

870 

880 

890  900  910;  921  931 

4 

426 

941!  951 

961 

972 

982 

992  *002  *012  »022  »f033 

5 

427 

63  043,  053 

063 

073 

083 

094  104  114  124  134 

6 

428 

144 1  155 

165 

175 

185 

195  205  215  225  236 

7 

429 

246 j  256 

266 

276 

286 

296!  306  3171  327  337 

8 

8.0 

9 

SO 

430 

347 

i£! 

"367 
468 

177JJ87 

4781  488 

~397-"407,"4T7,"428  "438 
^98  "508  "518  "528  "538 

431 

448 

458 

432 

548 

458 

568 

579!  589 

599  609  619  629  639 

433 

649 

659 

669 

679 i  689 

699  709!  719  729  739 

434 

749 

759 

769 

779 1  789 

799  809  819  829  839 

435 

849!  859 

869 

879  889 

899  909  919  929  939 

436 

949 

959 

969 

979  988 

998  «008  *018  *028  *038 

9 

437 

64  048 

058 

068 

078  088 

098  108!  118  128  137 

0  9 

438 

147 

157 

167 

177 1  187 

197i  2071  217  227  237 

439 

246 

256 

_266 

276 j  286 

296  306  316  326  335 

440 

345,  355 

365 

375,  385 

395,  404  414  424  434 

441 

444 

454 

464 

473 

483 

493  503  513  523  532 

442 

542 

552 

562 

572 

582 

591  601  61 ll  621  631 

443 

640 

650 

660 

670 

680 

689!  699|  709  719  729 

444 

738 

748 

758 

768 

777 

787;  797 1  807  816!  826 

445 

836 

816 

856 

865 

875 

885!  8951  904  914!  924 

446 

933 

943 

953 i  963!  972 

982!  992  *002!»011,#O21 

447 

65  031 

040 

050 

060  070 

079  089!  0991  108  118 

448 

128 

137 

147 

157  167 

176'  186|  196'  205]  215 

449 

225 

234 

244 

2541  263 

273  283  292  302  312 

450 

321 

331 

341 

350  360 

"369  "379  ^89  198 1  408 

N. 

L.O 

1 

2 

3 

4 

5   6   7 

T 

9 

P.P. 

LOGARITHMS 


53 


Table— ( Continued). 


N. 

L.O 

1 

2 

3 

4 

5  1 

6 

7  1  8 

9 

P.  P. 

450 

65  321 

13T 

^41 

"350 

l60 

"369 

"379  "389!^98 

^08 

451 

418 

427 

437 

447 

456 

466 

475'  485  495 

504 

452 

514 

523 

533 

543 

552 

562 

571  581  591 

600 

453 

610 

619 

629 

639 

648 

658  j 

667  677 

686 

696 

454 

706 

715 

725 

734 

744 

753 

849! 

763  772 

782 

792 

455 

801 

811 

820 

830 

839 

858  868 

877 

887 

456 

896 

906 

916 

925 

935 

944 

954'  963  973'  982 

m 

457 

992 

*001 

#011 

*020 

*030 

*039  *049  *058  »068  «077 

1 

1.0 

458 

66  087 

096 

106 

115 

124 

134 

143  153  182,  172 

2 

2.0 

459 

181 

191 

200 

210 

219 

229 

238  247  257!  266 

3 

3.0 

460 

276 

^85 

"295 

-Wi 

^14 

3p 

"^32  "342  "351  "361 

4 
5 

4.0 
5.0 

461 

370 

"380 

"389 

393 

"408 

417 

1271^436  "iiSlISS 

6 

7 
8 
9 

6.0 

7.0 
8.0 
9.0 

462 

464 

474 

483 

492 

502 

511| 

521  530  539  549 

463 

558 

567 

577 

586 

596 

605! 

614  624  633;  642 

464 

652 

661 

671 

680 

689 

699 

708  717  7271  738 

465 

745 

755 

764 

773 

783 

792 

801  811  820  829 

466 

839 

848 

857 

867 

876 

885' 

894  904  913  922 

467 

932 

941 

930 

960 

969 

978, 

987!  997  *008^015 

468 

67  025 

034 

043 

052 

082 

071' 

080  089  099  108 

469 

117 

127 

136 

!45 

154 

164 

173  182  191  201 

470 

210 

219 

228 

237 

247 

256 

"265  "274  "284  ^93 

471 

302 

311 

1m 

330 

"339 

348 

"357  "367  "376  "385 

9 

472 

394 

403 

413 

422 

431 

440 

449  459  468  477 

1 

0.9 

473 

486 

495 

504 

514 

523 

532 

541  550  560  569 

2 

1.8 

474 

578 

587 

596 

605 

614 

624. 

633  642  651  680 

3 

2.T 

475 

689 

679 

688 

697 

-06 

715! 

7241  733  742  752 

3.6 

476 

761 

852 

770 
861 

779 

870 

788 
879 

797 

888 

806 
897' 

815;  825!  834  843 

6 

4.5 

5.4 

477 

906  916  925'  934 

478 

943 

952 

961 

970 

979 

988 

997  ^006  ^015  *024 

6.3 

479 

68  034 

043 

052 

081 

070 

079 

088  097  106  115 

7.2 

480 

124 

l33 

"142 

151 

"160 

189 

178  187 :  196  205 

1  a.i 

481 

215 

224 

233 

242 

251 

280 

269  278  287  296 

482 

305 

314 

323 

332 

341 

350! 

359  388  377  386 

483 

395 

404 

413 

422 

431 

440 

449  458  467  476 

484 

485 

494 

502 

511 

520 

529 

538  547  556  565 

485 

574 

583 

592 

801 

610 

619 

628  637  646  655 

486 

664 

673 

681 

690 

708 

717  728  735  744 

II 

487 

753 

762 

771 

780 

789 

797 

808  815  824  833 

1 

0  S 

488 

842 

851 

860 

869 

878 

886 

895  904  913  922 

2 

489 

931 

940 

949 

958 

966 

975 

984  993  ^002  ^^11 

3 

490 

69  020 

"028 

~037 

"046 

055 

064 

"073  "082  "090  "099 

4 
5 

491 

108 

~va 

l26 

135 

144 

152 

luu  Tfij  T79  "188 

6 

7 
8 
9 

492 

197 

205 

214 

223 

232 

241 

249  258  267,  276 

493 

2^5 

294 

302 

311 

320 

329 

338  348  355'  364 

494 

373 

381 

390 

399 

408 

417 

425  434  443  452 

495 

461 

469 

478 

487 

496 

504 

513  522  531 !  539 

496 

548 

557 

566 

574 

583 

592 

601  609:  618 i  627 

497 

636 

644 

653 

662 

671 

679 

688  697;  705!  714 

498 

723 

732 

740 

749 

758 

767 

775  784  7931  801 

499 

810 

819 
906 

827 
914 

836 
923 

845 
932 

854 
940 

862  871,  880 
949,  958  966 

888 
975 

500 

897 

N. 

L.O 

1 

2 

3 

4 

5 

6  1  7   8 

9 

P.  P. 

54 


LOGARITHMS 


Table— ( Continued) 

• 

N. 

L.O 

69"  897 

1   2 

3 

A 

5 

6   7 

8 

9 

r 

P. 

500 

'906|'9T4 

"923  932 

"940 

"949  "958 

966 

■975 

501 

984 

"992,*O01 

*010|'^)18 

*027 

*O36#044 

»053*062 

602 

70  070 

079 

088 

096 

105 

114 

122  131 

140!  148 

503 

157 

165 

174 

183 

191 

200 

209 

217 

226 

234 

504 

243 

252 

260 

269 

278 

286 

295 

303 

312 

321 

505 

329 

338 

346 

355 

364 

372 

381 

389 

398 

406 

606 

415 

424 

43.2 

441 

449 

458 

467 

475 

484 

492 

.». 

507 

501 

509 

518 

526 

535 

544 

552 

561 

569 

678 

508 

586 

595 

603 

612 

621 

629 

638 

646 

655 

663 

1.8 

609 

672 

680 

689 

697 

706 

714 

723 

731 

740 

749 

2;t 

510 

757 

"766 

774 

l83 

~791 

"800 

808 

817 

"825 

"834 

s 

S.» 
4.5 

6.4 
6.3 
7.2 
8.1 

511 

842 

~851 

l59 

868 

^6 

"8851^93 

"902 

910 

919 

512 

927 

935 

944 

952 

961 

969 

978 

986 

995 

*003 

513 

71  012 

020 

029 

037 

046 

054 

063 

071 

079 

088 

614 

096 

105 

113 

122 

130 

139 

147 

155 

164 

172 

515 

181 

189 

198 

206 

214 

223 

231 

240 

248 

257 

516 

265 

273 

282 

290 

299 

307 

315 

324 

332 

341 

517 

349 

357 

366 

374 

383 

391 

399 

408 

416 

425 

618 

433 

441 

450 

458 

466 

475 

483 

492 

500 

608 

619 

517 

525 

533 

542 

550 

569 

567 

575 

584 

692 

520 

600 

609 

"617 

625 

634 

642 

650 

659 

667 

675 

521 

684 

692 

700 

709 

717 

725 

734 

742 

750 

759 

8 

522 

767 

775 

784 

792 

800 

809 

817 

825 

834 

842 

1 

0.8 

523 

850 

858 

867 

875 

883 

892 

900 

908 

917 

925 

2 

1.6 

524 

933 

941 

950 

958 

966 

975 

983 

991 

999*008 

3 

2.4 

525 

72  016 

024 

032 

041 

049 

057 

066 

074 

0821  090 

4 

3.3 

526 

099 

107 

115 

123 

132 

140 

148 

156 

165  173 

6 

4.0 

527 

181 

189 

198 

206 

214 

222 

230 

239 

247 

255 

6 

4.8 

528 

263 

272 

280 

288 

296 

304 

313 

321 

329 

337 

7 

6.6 

529 

346 

354 
436 

518 

362 
444 
"526 

370 
452 
534 

378 
460 
~542 

387 
469 
550 

395 

477 
"558 

403 

485 
567 

411 
"493 

"575 

419 
~50i 
"583 

8 
9 

6.4 
7.2 

530 

428 

531 

509 

532 

591 

599 

607 

616 

624 

632!  640 

648 

656 

665 

533 

673 

681 

689 

697 

705 

713 

722 

730 

738 

746 

634 

754 

762 

770 

779 

787 

795 

803 

811 

819 

827 

535 

835 

843 

852 

860 

868 

876 

884 

892 

900 

908 

536 

916 

925 

933 

941 

949 

957 

965'  973 

981 

989 

7 

537 

997 

*006 

*014 

*022 

*030 

*0:!8!*046  «054 

«062 

#070 

0.7 

538 

73  078 

086 

094 

102 

111 

119 

127 

135 

143 

151 

1.4 

539 

159 

167 

175 

183 

191 

199 

207 

215 

223 

231 

2.1 

540 

~239 

"247 

^5 

263 

272 

280 

~288 

"m 

304 

"312 

2.8 

3.5 
4.2 
4.9 
5.6 
6.3 

641 

320 

128 

"33^ 

344 

352 

360 

368 

376 

384 

392 

542 

400 

408 

416 

424 

i32 

440 

448 

45(> 

464 

472 

543 

480 

488 

496 

504 

512 

520 

528 

5;-6 

544 

652 

544 

560 

568 

576 

584 

592 

600 

608 

6.6 

624 

632 

645 

640 

648 

656 

664 

672 

679 

687 

695 

703 

711 

646 

719 

727 

735 

743 

751 

759 

767 

775 

783 

791 

647 

799 

807 

815 

823 

830 

838 

846 

854 

862 

870 

548 

878 

886 

894 

902 

910 

918 

926 

933 

941 

949 

649 

957 

965 

973 

981 

989 

997 

#005 

*013 

»020 

#028 

550 

74  036 

"044 

"052 

060 

068 

076 

084 

092 

^9 

107 

N. 

L.O 

1 

2 

3 

4 

5 

6 

7 

8 

9 

P 

P. 

LOGARITHMS 


55 


Table— 

( Continued) 

• 

N. 

L.O 

1 

2 

3 

4 

5 

6 

7   8 

9 

P.P. 

550 

74  036 

"044 

"052 

"060 

"068 

"076 

"084 

~092  "099!  107 

551 

115 

123 

131 

139 

147 

l55 

162 

170  178;  186 

552 

194 

202 

210 

218 

225 

233 

241 

24«i  257'  265 

553 

273 

280 

288 

296 

304 

312 

320 

327 1  335 1  343 

554 

351 

359 

367 

374 

382 

390 

398 

40k|  414  421 

555 

429 

437 

445 

453 

461 

468 

476 

484!  492 i  500 

556 

507 

515 

523 

531 

539 

547 

554 

5621  570!  578 

557 

586 

593 

601 

609 

617 

624 

632 

640  6481  656 

568 

663 

6711  679 

687 

695 

702 

710 

718,  726!  733 

559 

741 

749  757 

764 

772 

780 

788 

796  803 1  811 

560 

819 j  827  834 

"842 

"850 

"858 

865 

873  881  889 

,  A 

561 

896|  904  912 

920 

927 

"935 

"943 

"950 1 "958  "966 

562 

9-4 

9811  989 

997 

*005 

*012 

*020 

«028:*035  *043 

2 

u.o 
1.6 
2.4 
3.3 
4.0 
4.8 
5.6 
6.4 
7.2 

563 

75  051 

059 1  066 

074 

082 

089 

097 

105 

113  120 

564 

128 

136i  143 

151 

159 

166 

174 

182 

189  197 

565 

205 

213|  220 

228 

236 

243 

251 

259 

266  274 

566 

282 

289 

297 

305 

312 

320 

328 

335 

343  351 

567 

358 

366 

374 

381 

289 

397 

404 

412 

420 1  427 

568 

435 

442 

450 

458 

465 

473 

481 

488 

496 1  504 

569 

511 

519 

526 

534 

542 

549 

557 

565 

572  580 

570 

587 

^95 

603 

610 

618 

626 

633 

641  648 j  656 

571 

664 

~671 

"679 

~686 

"694 

"702 

709 

717|  724i  732 

572 

740 

747 

755 

762 

770 

778 

785 

793 1  800 !  80» 

573 

815 

823 

831 

838 

846 

853 

861 

868!  8761  884 

574 

891 

899 

906 

914 

921 

929 

937 

944  952!  959 

575 

967 

974 

982 

989 

997 

*005 

*012 

*020  *027  *035 

576 

76  042 

050 

057 

065 

072 

080 

087 

095!  103  110 

577 

118 

125 

133 

140 

148 

155 

163 

170 

1781  185 

578 

193 

200 

208 

215 

223 

230 

238 

245 

253 1  260 

579 

268 

275 

283 

290 

298 

305 

313 

320 

328  335 

580 

343 

350;  358 
425  433 

^5 
440 

373 

448 

380 
455 

"388 
462 

"395: "4031 "410 
"470,"477l~485 

581 

418 

7 

582 

492 

500  507 

515 

522 

530 

537 

545;  552 i  559 

1 

0.7 

583 

567 

574!  582 

589 

597 

604 

612 

619;  626  634 

2 

1.4 

584 

641 

649 1  656 

664 

671 

678 

686 

693,  701  708 

3 

2.1 

585 

716 

7231  730 

738 

745 

753 

760 

768!  775  782 

2.8 

586 

790 

797 

805 

812 

819. 

827 

834 

842  849,  856 

3.5 

587 

864 

871 

879 

886 

893 

901 

908 

916:  923  930 

4.2 

588 

938 

945 

953 

960 

967 

975 

982 

989!  997  *004 

4.9 

589 

77  012 

019 

026 

034 

041 

048 

056 

063 

070|  078 

5.6 
6.3 

590 

085 

093 

100 

"107 

IT5 

"122 

I29 

137 

144 

151 

691 

159 

1661  173 

181 

188 

"195 

^03 

"2T0 

"217 

225 

592 

232 

240!  247 

254 

262 

276 

283 

291 

298 

593 

305 

313 

320 

327 

335 

342 

349 

357 

364 

371 

594 

379 

386 

393 

401 

408 

415 

422 

430 

437 

444 

595 

452 

459 

466 

474 

481 

488 

495 

503 

510 

517 

596 

525 

532 

539 

546 

554 

561 

568 

576 

583 

590 

597 

597 

605 

612 

619 

627 

634 

641 

648 

656 

663 

598 

670 

677 

685 

692 

699 

706 

714 

721 

728 

735 

599 

743 

750 
822 

757 
830 

764 
837 

772 
"844 

779 
~851 

786 
«59 

793 
"866 

801 
"873 

808 
^80 

600 

815 

N. 

L.O 

1 

2 

3 

4 

5 

6 

7 

~8~ 

9 

P.P. 

56 


LOGARITHMS 


Table— ( Continued). 


N. 

L.O 

1 

2 

3 

4 

5 

6 

7 

8 

9 

p.  p. 

600 

77  815 

"822 
895 

"830 
902 

"837 
909 

^44 
916 

J51 
924 

"859 
931 

166 
938 

"873 
945 

"880 
952 

601 

887 

602 

960 

967 

974 

981 

988 

996 

*003 

*010 

*017 

*025 

603 

78  032 

039 

046 

053 

061 

068 

075 

082 

089 

097 

604 

104 

111 

118 

125 

132 

140 

147 

154 

161 

168 

605 

176 

183 

190 

197 

204 

211 

219 

226 

233 

240 

606 

247 

254 

262 

269 

276 

283 

290 

297 

305 

312 

8 

607 

319 

326 

333 

340 

347 

355 

362 

369 

376 

383 

1 

0.8 

608 

390 

398 

405 

412 

419 

426 

433 

440 

447 

455 

2 

1.6 

609 

462 

469 

476 

483 

490 

497 

504 

512 

519 

526 

3 

2.4 

610 

533 

540 
611 

547 
618 

625 

"56T 
633 

"569 
640 

576 
647 

^83 
654 

590 
661 

597 

668 

4 
5 
6 
7 
8 
9 

3.2 
4.0 
4.8 
5.6 
6.4 
7.2 

611 

604 

612 

675 

682 

689 

696 

704 

711 

718 

725 

732 

739 

613 

746 

753 

760 

767 

774 

781 

789 

796 

803 

810 

614 

817 

824 

831 

838 

845 

852 

859 

866 

873 

880 

615 

902 

909 

916 

923 

930 

937 

944 

951 

616 

958 

965 

972 

979 

986 

993 

*000 

*007 

*fll4 

*021 

617 

79  029 

036 

043 

050 

057 

064 

071 

078 

085 

092 

618 

099 

106 

113 

120 

127 

134 

141 

148 

155 

162 

619 

169 

176 

183 

190 

197 

204 

211 

218 

225 

232 

620 

239 

246 
"316 

253 
323 

260 
^30 

267 
337 

274 
344 

"281 
~35T 

288 

295 

302 
372 

621 

309 

358!  365 

7 

•  622 

379 

38fi 

393 

400 

407 

414 

421 

428 

435 

442 

1 

0.7 

623 

449 

456 

463 

470 

477 

484 

491 

498 

505 

511 

2 

1.4 

624 

518 

525 

632 

539 

546 

553 

560 

567 

574 

581 

3 

2.1 

625 

588 

595 

602 

609 

616 

623 

630 

637 

644 

650 

4 

2.8 

626 

657 

664 

671 

678 

685 

692 

706 

713 

720 

5 

3.5 

627 

727 

734 

741 

748 

754 

761 

768 

775 

782 

789 

6 

4.2 

628 

796 

803 

810 

817 

824 

831 

837 

844 

851 

858 

7 

4.9 

629 

865 

872 

879 

886 

893 

900 

906 

913 

920 

927 

8 
9 

5.6 

6.8 

630 

934 

"94T 
"010 

"948 

"on 

"955 
"024 

~962 
1(30 

^9 
~037 

^75 
044 

~982 
"051 

989 
"058 

996 
"065 

631 

80  003 

632 

072 

079 

085 

092 

099 

106 

113 

120 

127 

134 

633 

140 

147 

154 

161 

168 

175 

182 

188 

195 

202 

634 

209 

216 

223 

229 

236 

243 

250 

257 

264 

271 

635 

277 

284 

291 

298 i  305 

312 

318 

325 

332 

339 

636 

346 

353 

359 

366!  373 

380 

387 

393 

400 

407 

A 

637 

414 

421 

428 

434 

441 

448 

455 

462 

468 

475 

06 

638 

482 

489 

496 

502 

509 

516 

523 

530 

536 

543 

1.2 

639 

650 

557 
"625 

564 
632 

570 
638 

577 
645 

584 
652 

591 
659 

598 

604 

611 
679 

9 

1.8 

640 

618 

665  672 

2.4 
3.0 
3.6 
4.2 
4.8 
5.4 

641 

686 

693 

699 

706  713 

720 

726 

"733 1  "740 

747 

642 

754 

760 

767 

774 

781 

787 

794 

801 1  808 

814 

043 

821 

828 

835 

841 

848 

855 

862 

8681  875 

882 

644 

889 

895 

902 

909 

916 

922 

929 

936  943 

949 

645 

956 

963 

969 

976 

983 

990 

996 

#003  *010 

»017 

646 

81  023 

030 

037 

043 

050 

057 

064 

070  077 

084 

647 

090 

097 

104 

111 

117 

124 

131 

I37I  144 

151 

648 

158 

164 

171 

178 

184 

191 

198 

204  211 

218 

649 

224 

231 

238 

245 

251 

258 

265 

271 

278 

285 

650 

291 

298 

l05 

311 

318 

J25 

"331 

"338 

"345 

351 

N. 

L.O 

1 

•2 

3 

4 

5 

6 

7 

8 

9 

P.  P. 

LOGARITHMS 


57 


Table— 

{Continued). 

N. 

L.O 

i  1   2  1  3 

|4 

5  1  6  1  7 

8   9 

P.P. 

650 

81  291 

"298i'305i"3TT 

318 

325,  331 j "338 

"345  "351 

651 

358 

365:  371  37h 

"3S5 

391 

398 1  405 

411  418 

652 

425 

431  438 

445 

451 

458 

465 

471 

478  485 

653 

491 

498 i  505 

511 

518 

525 

531 

538 

544  551 

654 

558 

564  571 

578 

584 

591 

598 

604 

61li  617 

655 

624 

631  637 

644 

651 

657 

664 

671 

6771  684 

656 

690 

697 1  704 

710 

717 

723 

730 

737 

743  750 

657 

757 

763:  770i  776 

783 

790 

796 

803 

809  816 

658 

823 

829,  8361  842 

849 

856'  862,  869 

875  882 

659 

889 

895  902 1  908 

915 

921  928 i  935 

941  948 

660 

954 

961  968  974 

981 

987 

994  *000 

*00"7  *014 

661 

S2  020 

~027  ~033  "040 

W6 

"053 

"060  ^066 

073  079 

7_ 

662 

086 

092  099  105 

112 

119 

125!  132 

138  145 

1 

0.7 

663 

151 

158  164!  171 

178 

184 

191 1  197 

204  210 

2 

1.4 

664 

217 

223  230 

2?6 

243 

249 

256  263 

3 

665 

282 

289  295 

302 

308 

315 

321 !  328 

334  341 

4 

666 

347 

354  360 

367 

373 

S80 

3871  393 

400  406 

5 

667 

413 

419  426 

432 

439 

445  452 1  458 

465,  471 

6 

668 

478 

4841  491'  497 

504 

510  5171  523 

530  536 

7 

669 

543 

549  556  562 

569 

575 1  582  588 

595  601 

8 
9 

670 

607 

614  620  627 

633 

640  "646  653 

659  666 

671 

672 

"679  "685|~692 

~698 

'705'"7Tl  ^718 

"724|-730 

672 

737 

743:  750 j  756 

763 

7691  776 

782 

789 1  795 

673 

802 

808:  814!  821 

827 

834  840 

847 

853!  860 

674 

866 

8721  8791  885 

892 

898  905 

911 

918'  924 

675 

930 

837  943!  950 

956 

963  969 

975 

982  988 

676 

995  *001  #008>014 

*020 

*027,»033;*040 

*046;*052 

677 

83  059 

065 i  072 

078 

085 

091 1  097  104 

no!  117 

678 

123 

129!  136 

142 

149 

1551  161  168 

174  181 

679 

187 

193 

200 

206 

213 

2191  225  232 

238:  245 

680 

251 

257 

264 

270 

276 

283  289  296 

302  308 

681 

315 

321 

327 

l34 

"340 

"347 

353 

359 

"366  "372 

6 

682 

378 

385 

391 

398 

404 

410 

417 

423 

429  436 

1 

0.6 

683 

442 

448 

455 

461 

467 

474 

480 

487 

493  499 

3 

1.2 

684 

506 

512 

518 

525 

531 

537 

544 

550 

556  563 

3 

1.3 

685 

569 

575 

582 

588 

594 

601 

607 

613 

620  626 

4 

2.4 

686 

632 

639 

645 

651 

658 

664 

670 

677 

683  689 

5 

3.0 

687 

696 

702 

708 

715 

721 

727 

734,  740 

746  753 

6 

3.6 

688 

759 

765  771 

778 

784 

790 

797  803 

809  816 

7 

4.2 

689 

822 

828  835 

841 

847 

853 

860  866 

872  879 

8 

4.3 

690 

885 

891 
954 

-897 
960 

904 
967 

910 
973 

916 
979 

923 1  929 
985 i  992 

"935  "942 
998  *004 

» 

5.4 

691 

948 

692 

84  Oil 

017 

023 

029 

036 

042 

048 

055 

061  067 

693 

073 

080 

086 

092 

098 

105 

111 

117 

123  130 

694 

136 

142 

148 

155 

161 

167 

173 

180 

186  192 

695 

198 

205 

211 

217 

223 

230 

236 

242 

248  255 

696 

261 

267 

273 

280 

286 

292 

298  305 

311  317 

323 

330 

336'  342 

348 

354 

361 :  367 

373  379 

698 

386 

392 

398!  404 

410 

417 

4231  429 

435 1  442 

699 

448 

454 
516 

460 
~522 

466 

~528 

473 
535 

479 
541 

485  491 
l47^ 

497  504 
"559  ~566 

700 

510 

N. 

L.O 

1 

2 

3 

4 

5 

6 

' 

8   9 

P.P. 

58 


LOGARITHMS 


Table— 

(.Continued) 

• 

N. 

L.O 

1 

2 

3 

4 

5 

6 

' 

8  1  9 

P.P. 

700 

84  510 

"516 

"522 

"528 

T35 

"541 

"547 

"553 

"559  "566 

701 

572 

578 

584 

590 

597 

"603 

"609 

615 

621  628 

702 

634 

640 

646 

652 

658 

665 

671 

677 

683  689 

703 

696 

702 

708 

714 

720 

726 

733 

739 

745  751 

704 

757 

763 

770 

776 

782 

788 

794 

800 

907 1  813 

705 

819 

825 

831 

837 

844 

850 

856 

862 

868  874 

706 

880 

887 

893 

899 

905 

911 

917 

924 

930  936 

7 

707 

942 

948 

954 

960 

967 

973 

979 

9911  997 

0.7 

708 

85  003 

009 

016 

022 

028 

034 

040 

046 

052'  058 

709 

065 

071 
132 

077 
138 

083 
144 

089 
150 

095 
156 

101 
163 

107 
169 

114  120 
I75J  181 

8 
9 

710 

126 

sis 

6.S 

711 

187 

193 

199 

205 

211 

217 

224 

230 

236  242 

712 

248 

254 

260 

266 

272 

278 

285 

291 

297  i  303 

713 

309 

315 

321 

327 

333 

339 

345 

352 

358  364 

714 

370 

376 

382 

388 

394 

400 

406 

412 

418  425 

715 

431 

437 

443 

449 

455 

461 

467 

473 

479,  485 

716 

491 

497 

503 

509 

516 

522 

528 

534 

540  646 

717 

652 

558 

564 

570 

576 

582 

588 

594 

600  606 

718 

612 

618 

625 

631 

637 

643 

649 

655 

661  667 

719 

673 

679 

685 

691 

697 

703 

709 

715 

721:  727 

720 

733 

739 

745 

751 

757 

^63 

"^69 

T75 

"781, "788 

721 

794 

800 

806 

812 

818 

824 

830 

"836 

842'  848 

8 

722 

854 

860 

866 

872 

878 

884 

890 

896 

902,  908 

0.5 

723 

914 

920 

926 

932 

938 

944 

950 

956 

962  968 

1.2 

724 

974 

980 

986 

992 

998 

*004 

*010 

#016 

*022  »028 

1.8 

725 

86  034 

040 

046 

052 

058 

064 

070 

076 

082!  088 

2.4 

726 

094 

100 

106 

112 

118 

124 

130 

136 

141 !  147 

3.0 

727 

153 

159 

165 

171 

177 

183 

189 

195 

201  207 

3.6 

728 

213 

219 

225 

231 

237 

243 

249 

255 

261  267 

4.2 

729 

273 

279 

285 

291 

297 

303 

308 

314 

320  326 

4.3 

730 

332 

338 

344 

~35l) 

"356 

"362 

368 

3-4 

380 :  386 

731 

392 

398 

~404 

lio 

~415 

421 

427 

433 

439,  445 

732 

451 

457 

463 

469 

475 

481 

487 

493 

499;  604 

733 

510 

516 

522 

528 

534 

540 

546 

552 

558  564 

734 

570 

576 

581 

587 

593 

599 

605 

611 

617  623 

735 

629 

635 

641 

646 

652 

658 

664 

670 

676  682 

73fi 

688 

694 

700 

705 

711 

717 

723 

729 

735;  741 

s 

737 

747 

753 

759 

764 

770 

776 

782 

788 

794 1  800 

0.5 

738 

806 

812 

817 

823 

829 

835 

841 

847 

853!  859 

1.0 

739 

864 

870 

876 

882 

894 

900 

906 

911  917 

1.5 

740 

~923 

929 

935 

"941 

"947 

"953 

958 

"964 

976 1  976 

8 

2.0 
2.5 
3.0 
3.5 
4  0 

741 

9H2 

"988 

"994 

"999 

*005 

»ori 

»017 

#023 

*«29  ^35 

742 

87  040 

046 

052 

058 

064 

070 

075 

081 

087  093 

743 

099 

105 

111 

116 

122 

128 

134 

140 

•146  151 

744 

157 

163 

169 

1-5 

181 

186 

192 

198 

204  210 

4.5 

745 

216 

221 

227 

233 

239 

245 

251 

256 

262  268 

746 

274 

2H0 

2H6 

291 

297 

303 

309 

315 

320 1  826 

747 

332 

338 

344 

349 

355 

361 

367 

373 

379  384 

748 

390 

396 

402 

408 

413 

419 

425 

431 

437  442 

749 

448 

454 

460 

466 

371 

477 

483 

489 

495]  600 

750 

506 

~612 

518 

;623 

529 

535 

541 

647 

552 

558 

N. 

L.0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

P.  P. 

LOGARITHMS 


59 


Table— ( Continued). 


N. 

L.0 

87  506 

1 

"512 

2 

"518 

3 

"523 

4 

~b29 

5 

-535 

6 

"541 

7  1  8  !  9 

P 

P. 

750 

^47;-552  "558 

751 

564 

570 

576 

581 

"587 

"593 

599 

6041  610  616 

752 

622 

628 

633 

639 

045 

651 

656 

662  668  674 

753 

679 

685 

691 

697 

703 

708 

714 

720;  726  731 

754 

743 

749 

754 

760 

766 

772 

777,  783  789 

755 

795 

800 

806 

812 

818 

823 

829 

835'  841  846 

756 

852 

858 

864 

875 

881 

887 

892  898  904 

757 

910 

915 

921 

927 

933 

938 

944 

950  955  961 

758 

967 

973 

978 

984 

990 

996 

*001 

*007  »013  >01(- 

759 

88  024 
081 

030 
"087 

036 

041 

047 

053 

058 

064  070  076 

760 

"093 

098 

104 

110 

116 

121  127  133 

761 

138 

144 

lob 

"156 

161 

"167 

173 

178  184  190 

6 

762 

195 

201 

20- 

213 

218 

224 

230 

235  241  247 

0.6 

763 

252 

258 

264 

270 

275 

281 

287 

292  298  304 

1.2 

764 

309 

315 

32] 

326 

332 

338 

343 

349  355  360 

1.3 

765 

366 

372 

377 

383 

389 

395 

400 

406  412  417 

2.4 

766 

423 

429 

434 

440 

446 

451 

457 

463  468  474 

3.0 

767 

480 

485 

491 

497 

502 

508 

513 

519  525  530 

3.6 

768 

536 

542 

547 

553 

559 

564 

570 

576  581  587 

*l 

769 

593 

598 

604 

610 

615 

621 

627 

632  638  643 

8 

*•! 

770 

649 

655 

660 

"666 

672 

677 

683 

689  694  700 

9  1  ^.s 

771 

705 

711 

717 

-72'2 

728 

734 

739 

745  750  756 

772 

762 

767 

773 

779 

784 

790 

795 

801  807  812 

773 

818 

824 

829 

835 

840 

846 

852 

857  863  868 

774 

874 

880 

885 

891 

897 

902 

908 

913  919  925 

775 

930 

936 

941 

947 

953 

958 

964 

969  975  981 

776 

986 

992 

997 

*003 

»009 

*014 

*020 

*025  *031  '037 

777 

89  042 

048 

053 

059 

064 

070 

076 

081  087  092 

778 

098 

104 

109 

115 

120 

126 

131 

137  143  148 

779 

154 

159 

165 

170 

176 

182 

187 

193  198  204 

780 

209 

215 

221 

226 

"232 

^37 

"243 

"248  "254  "260 

781 

265 

Tri 

-276 

282 

"287 

"293 

"298 

304  310  315 

5 

782 

321 

326 

332 

337 

343 

348 

354 

360  365  371 

1 

0.5 

783 

376 

382 

387 

393 

398 

404 

409 

415  421  426 

2 

1.0 

784 

432 

437 

443 

448 

454 

459 

465 

470  476  4M 

3 

1.5 

785 

487 

492 

498 

504 

509 

515 

520 

526  531  537 

4 

2.0 

786 

542 

548 

553 

559 

564 

5-0 

575 

581  5S6  592 

5 

2.5 

787 

597 

603 

609 

614 

620 

625 

631 

636  642  647 

6 

3.0 

788 

653 

658 

664 

669 

675 

680 

686 

691  697  702 

7 

3.5 

789 

708 

713 

719 

724 

730 

735 

741 

746  752  75T 

8 

4.0 

790 

763 

768 

774 

"779 

785 

790 

796 

801  807  812 

9 

4.5 

791 

818 

"823 

"829 

"834 

840 

"845 

"851 

856  862  ^67 

792 

873 

878 

883 

889 

894 

900 

905 

911  916  922 

793 

92- 

933 

938 

944 

949 

955 

960 

966  971  977 

794 

982 

988 

993 

998 

»«04 

*009 

*015 

*020  *026  '■031 

795 

90  037 

042 

048 

053 

059 

064 

069 

075  080  086 

796 

091 

097 

102 

108 

113 

119 

124 

129  135  140 

797 

146 

151 

157 

162 

168 

173 

179 

184  189  195 

798 

200 

206 

211 

217 

222 

227 

233 

238  244  249 

799 

255 

260 

266 

271 

276 

282 

287 

293  298  304 

800 

309 

314 

820 

325 

331 

336 

342 

"347  "352  "358 

N. 

L.O 

1 

2 

3 

4 

5 

T 

7  1  8  1  9 

P.P. 

60 


LOGARITHMS 


Table— 

( Continued] 

. 

N. 

L.0|  1   2   3   4 

5   6   7  1  8 

9 

P.P. 

800 

90  309  314  320  325 |  331 

l36  ir2  "347|'352 

"358 

801 

363;  369  2741  380  385 

390 

396  401 

407 

412 

802 

417  423  428  434  439 

445 

450!  455 

461 

466 

803 

472  477  482  488  493 

499 

504 

509 

515 

520 

804 

526  531 1  636  542'  547 

553 

558 

563 

569!  574 

805 

580'  585'  590 j  5961  601 

607 

612 

617 

623 

628 

806 

634  639 i  644!  650 1  655 

660 

666 

671 

677 

682 

807 

687  693.  698.  703  709 

714 

720 

725 i  730 

736 

808 

7411  747;  752!  757  763 

768 

773!  779!  T84 

789 

809 

7951  800;  806!  811  816 

822 

827  8321  838 

843 

810 

849;  8541  859  865 |  870 

^75  88l!'886i  891 

"897 

811 

902,  907  913  918  924 

929 

934'  940  945  950 

.8 

812 

956  961  966  972 

977 

982 

988  9931  998.*004 

813 

91  009  014  020  i  025 

030 

036 

041  046  052 

057 

814 

062,  068.  0731  078 

084 

094  100  105 

110 

815 

116'  121 

126 

132 

137 

142 

148;  153!  158 

164 

816 

169 

174 

180 

185 

190 

196 

201 !  206'  212 

217 

817 

222 

228 

233 

238 

243 

249 

254!  259,  265 

270 

818 

275 

281 

286 

291 

297 

302 

307!  312 1  318 

323 

819 

328 

334 

339!  344 

350 

355 

360  365  371 

376 

9 

820 

381 i  387  392]  397 

403 

408i  413!  418;  424 

429 

821 

434!  4401  445 

450 

455 

"461  '466!'471'~477 

482 

822 

487 1  492  498 

503 

508 

514  519!  524  529 

535 

823 

540 1  545!  551 

556 

561 

566  572!  5771  582!  587 

824 

5931  598  603 

609 

614 

619  624  630  635  640 

825 

645 

651  656 

661 

666 

672!  6771  682;  687 

693 

826 

698 

703  709 

714 

719 

724  730 !  7351  740 

745 

827 

751 

756  761 

766 

772 

777  782 1  787  793 

798 

828 

803 

808  814 

819 

824 

829  834!  840  845 

850 

829 

855 

861  866 

871 

876 

882 j  887 j  892 

897 

903 

830 

908 

913  918 

924 1  929 

934'  939 

944 

950 

"955 

831 

960 

965  971 

976 

981 

986 

991 

997 

*002 1*007 

5 

832 

92  012 

018  023 

028 

033 

038 

044 

049 

054  059 

1 

0.5 

833 

065 

070  075 

080 

085 

091 

096 

101 

106  111 

3 

1.0 

834 

117 

122  127 

132 

137 

143 

148 

153 

158  163 

3 

1.5 

835 

169 

174  179 

184 

189 

195 

200 

205  210'  215 

4 

2.0 

836 

221 

226  231 

236 

241 

247 

252 

257  262 

267 

5 

2.5 

837 

273 

278  283 

288 

293 

298 

304 

309  314 

319 

6 

3.0 

838 

824 

330  335  340 

345 

350 

355 

361  366 

371 

7 

3.5 

839 

376 

381;  387!  392  397 

402 

407  412  418 

423 

8 

4.0 

840 

428  433 1  438;  443 ^  449 

^454 

"459i"46ll"469 

474 

9 

4.5 

£41 

4801  485  490,  495!  500 

505 

'5lii~5i6r521 1526 

842 

531  536  542 

547!  552 

557 

562 i  567!  572 

578 

843 

583  588  593 

5981  603 

609 

614  619 

624 

629 

844 

634!  639  645 

650  655 

660 

665  670 

675 

681 

845 

686  691  696 

701 1  706 

711 

716  722 

727 

732 

846 

737  742'  747 

7521  758 

763  768  773 

778 

783 

847 

788  793  799 1  804  i  809 

814  819  824 

829 

334 

848 

840  845'  850,  855 

860 

865 

870  875 

881 

886 

849 

891  996  901  906 

911 

916 

921  927 

932 

937 

850 

942  947 

952  957 

962 

967 

973 

978 

988 

988 

N. 

L.O 

1 

2   3 

4 

5 

6 

7 

8 

9 

P.P. 

LOGARITHMS 


61 


Table— ( Continued). 


N. 

L.O 

1 !  2 1 3  r-4 

5   6 

' 

8   9 

P.  P. 

850 

92  942 1  947'  952 1  9571  962 

"967  "973 1 "978 

"983  "988 

851 

993,  998  *«03,*<)08  »013 

K)18,»O24»029*034  *039 

852 

93  044;  049  0541  0591  064 

0691  075  OsO 

085;  090 

853 

0951  lOOl  105  1101  115 

120 

125  131 

136  141 

854 

146  15l[  156|  161 

166 

171 

176  181 

186]  192 

855 

197 

202!  207!  212 

217 

222 

227  232 

237!  242 

856 

247 

2521  258!  263 

268 

273 

278  283 

288]  293 

fl 

85" 

298 

303  308!  313 

318 

323 

328  334 

339  344 

1 

0  s 

8=i8 

349 

354 i  359  364 

369 

374 

379  384 

389  394 

2 

1.2 

859 

399 

404!  409!  414 

420 

425 

430  435 

440 :  445 

3 

1.3 

860 

4501  455  460  465 

~470 

475 

~480  "485 

490  495 

4 
5 

2.* 
3  9 

861 

5001  505  510  515 

"520 

^26 

~531|"536 

~541:"546 

6 

7 
8 
9 

4.3 
5.4 

862 

551  556,  5611  566 

571 

576 

581]  586 

591)  596 

863 

601  6061  611 1  616 

621 

626 

631  636 

641!  646 

864 

651  656  661 

666 

671 

676 

682  687 

8921  897 

865 

702  7071  712 

717 

722 

727 

732!  737 

742 1  747 

866 

752  757  762 

767 

772 

777 

782]  787 

792 1  797 

867 

802 !  807 !  812 

817 

822 

827 

832;  837 

842;  847 

868 

852 

8571  862 

867 

872 

877 

882]  887 

892 1  897 

869 

902 

907  912 

917 

922 

927 

932  937 

942 1  947 

870 

952 

957,  962 i  967 i  972 
"007  1)12  "on, "022 

977 

982  987 

992,  997 
1)42  ~047 

871 

94  002 

"0271^32  T37 

5 

872 

052 

057  062 

067  072 

077 

082 

086 

0911  096 

1 

0.5 

873 

101 

106  HI 

116  121 

126 

131 

136 

141  146 

2 

1.0 

874 

151 

156  161 

166!  171 

176 

181 

186 

191 1  196 

3 

1.5 

875 

201  206  211 

216|  221 

226 

231 

236  i 

240]  245 

4 

2.0 

876 

250  255  260 

265  270 

275 

280 

285 

290 i  295 

5 

2.5 

877 

300 

305,  3101  315  320 

325 

330  335 

340  345 

6 

3.0 

878 

349 

354  359!  364  369 

374 

379!  384 

389 1  394 

T 

3.5 

879 

399 

404:  4091  414  419 

424 

429  433 

4381  443 

8 
9 

4.0 
4.5 

880 

448 

453  458 1  463  468 

^l 

478  483 
"527(~532, 

488,  493 
537  542 

881 

498 

"563  ~507i~5r21~5r7 

882 

547  552  5571  562 i  567 

571 

5761  581 ! 

586:  591 

883 

596  601  606  611.  616 

621  626!  630 

635  640 

884 

645  650  655  660  665 

670 

675  680 

685,  689 

885 

694|  699  704;  709,  7U 

719 

724,  7291 

734:  738 

886 

743:  748  7531  758 1  763 

768 

773:  7-8 

783  787 

4 

887 

792'  797  802  8071  812 

817 

822]  827 

8321  836 

1 

0.4 

888 

841 i  846  851  856  861 

866 

871 !  876 

880]  885 

2 

0.8 

889 

890]  895;  900  905]  910 

915 

919!  924 

929  934 

3 

1.2 

890 

939  944  949  954  959 

963!  968  973 

"978 

983 

1.6 
2.0 
2.4 

891 

983,  993,  998  #002  #007 

*012  *017,*022  »027 

*032 

892 

95  036  041  046  051;  056 

061 !  066 

071 

075 

080 

2  3 

893 

085  090,  095i  100|  105 

109  114 

119 

124 

129 

32 

894 

1341  139  1431  148!  153 

158  163 

168 

173 

177 

3.6 

895 

182 

1871  1921  197 i  202 

207  211 

216 

221 

226 

896 

231 

236  240  2451  250 

255  260]  265 

270 

2-4 

897 

279 

284  289  294|  299 

303!  308  313 

318 

323 

898 

328 

332  337:  342  347 

352!  357  361 

366 

371 

899 

376 

381  386  390  395 

400  405  410 

415 

419 

900 

424 

L.O 

^29  "434 

439 

444 

^448  ~453'^58 

463 

468 

N. 

1   2 

3 

4 

5   6  1  7 

T 

9 

P.P. 

LOGARITHMS 


Table— ( Continued). 


N. 

L.0ll|2|3 

4 

5 

6   7  1  8   9 

P.  P. 

900 

95  424  429  434  439 

~444 

~448 

^453  "458; "463 ["468 

901 

472  477  482 t  487 

"492 

^97 

501  506;  Cn  516 

902 

521  525  530 1  535 

540 

545 

550  554 j  559  564 

903 

569  574  578  583 

588 

593 

5981  602;  607!  612 

904 

617  622  626:  631 

636 

641 

646  650^  655  660 

905 

665i  670;  674  679 

684 

689 

694'  698'  703  708 

906 

713  7181  722 

727 

732 

737 

742;  746  751  756 

907 

761  766  770 

775 

780 

785 

789  794!  799'  804 

908 

809,  813  818 

823 

828 

832 

837  842;  8471  852 

909 

856!  861  866 

871 

875 

880 

885  890,  895!  899 

910 

904  909  914 

"918 

'92'3 

~928 

933!  938,  942  947 

911 

952  957  961 

"966 

~971 

976 

980  985'  990  995 

,   5 

912 

999  *004  *009  *014 

*019 

*023 

*028  *038  *038  *042 
076;  080!  085  090 

1 

0.5 

913 

96  047  052 1  057 

061 

066 

071 

2 

1.0 

914 

095  099  104 

109 

114 

118 

123 

128  133!  137 

3 

1.5 

915 

142  1471  152 

156 

161 

166 

171 

175!  180'  185 

4 

2.0 

916 

190  194  199 

204 

209 

213 

218 

223  2271  282 

5 

2.5 

917 

237;  '2421  246 

251 

256 

261 

265 

270  275 i  280 

6 

3.0 

918 

284:  289,  294 

298 

803 

308 

313 

317  322'  327 

7 

3.5 

919 

832  336  341 

346 

350 

855 

860 !  365'  869  374 

8 

4.0 
4.5 

920 

379,  884  388 

393 

398 

402 

"407  j  "412  "417  ^21 

921 

426  431  435 

"440 

~445 

~450 

"454|l59  l64  168 

922 

473  478'  483 

487 

492 

497 

501!  506!  511  515 

923 

520  525 1  530 

534 

539 

544 

548!  553;  558  562 

924 

567  572 j  677 

581 

586 

591 

595  600,  605!  609 

925 

614  619,  624 

628 

633 

638 

642,  647  652  656 

926 

661  666  i  670 

675 

680 

685 

689  694  6991  703 

927 

708  7131  717 

722 

727 

731 

736,  741'  745'  750 

928 

755 1  759  764 

769 

774 

778 

783  788!  792'  797 

929 

802  806  811 

816 

820 

825 

830 ;  834!  839!  844 

830 

848  853  858 

862 

"867 

872 

l76' "881,186  190 

931 

895  900  904 

~909 

914 

"918 

923  928  932  937 

4 

932 

942!  946  951 

956 

960 

965 

970  974  979  984 

1 

0.4 

933 

9M8  993  997 

*002 

*007 

*011 

*016  *021  »025  X030 

2 

0.8 

934 

97  035  039,  044 

049 

053 

058 

063  067  072  077 

3 

1.2 

935 

081 :  086  090 

095 

100 

104 

109  114  118  123 

4 

1.6 

936 

128;  132  137 

142 

146 

151 

155  160!  165  169 

5 

2.0 

937 

174!  179 

183 

188 

192 

197 

202  206  211  216 

6 

2.4 

938 

220  225 

230 

234 

239 

243 

248;  253:  257  262 

7 

2.8 

939 

267  271 

276 

280 

285 

290 

294  299  304  308 

8 

3.2 

9 

3.6 

940 

313  In 

322 

327 

331 

"336 

340  345  350  354 

941 

359  364  368 

373 

~377 

382 

"387i"391  ~396  lOO 

942 

405  410  414 

419 

424 

428 

433;  437,  442,  447 

943 

451  456  460]  465 

470 

474 

479  483  488  493 

944 

497  5(12  506  511 

516 

520 

525  529  534  539 

945 

543  548  552 1  557 

562 

566 

571  575  580 ;  585 

946 

589,  594,  59^  603 

607 

612 

617  621  626  630 

947 

635  640  644  64'.l 

653 

658 

663  667  672  676 

948 

681  685 

690  695 

699 

704 

708  713  717:  722 

949 

727  731 

736 

740 

745 

749 

754  759;  763  768 

950 

772  l77 

782 

786 

791 

795 

loo  loi  809  lis 

N. 

L.O  1 

2 

3 

4 

5 

~6  1  7   8   9 

P.P. 

LOGARITHMS 


63 


Table— ( Continued). 


N. 

L.O 

1   2   3  1  -I 

5   6  !  7   8   9 

P.P. 

950 

97  772 

Tn   l82  ^  "791 

~795|800'"804  "809  "813 

951 

818  823 1  8271  832  836 

~84l|"845  "850'1;55  ~859 

95J 

864  868'  873!  877  8b2 

886  891  896  900  905 

953 

909!  9u'  918'  923  928 

932  9371  941  946  950 

954 

955  959'  9641  868  973 

978:  982  987  991  996 

955 

98  OOOi  005  009:  014  019 

023;  028  032  037  041 

956 

046  050!  055 1  059  064 

068,  073  078  082  087 

957 

0911  096  100  105  109 

114'  118  123  127  132 

958 

137  1411  146  150  155 

159  164  168  173  177 

959 

182 1  186  191 i  195  200 

204  209  214  218  223 

960 

227  232 j  2361  241:  245 

250  '254  '259  263  268 

961 

272i  277]  281 1  286,  290 

295:  299  304,  3081  313 

5 

962 

3181  322'  327  331  336 

340  345  349  354'  358 

1  ~ ' 

u.» 

963 

363  367  372 1  3761  381 

385  390  394  399  403 

2 

1.0 

964 

408 

412  417  421  426 

430,  435  439  444  448 

3 

1.5 

965 

453 

4571  462  4661  471 

4751  480  484  489  493 

4 

2.0 
2.5 

966 

498 

502  507  511  516 

520  525  529  534  538 

5 

967 

543 

5471  552  556  561 

565  570  574  579  583 

6 

3.0 

968 

588 

592 i  597,  601  605 

610,  614  619  623  628 

7 

3.5 

969 

632 

637  641,  646  650 

6551  659  664  668  673 

8 
9 

4.0 
4.5 

970 

677  682,  686  691,  695 

^700  ^04  709  ^13,'717 

971 

722;  726;  731  735  740 

Tu  "749  ^53  ^58  "762 

972 

767l  771  7761  780  784 

789:  793,  798  802  807 

973 

811  8161  820'  825  829 

834  838  843  847  851 

974 

856'  860 1  865  869  874 

878  883  887  892  896 

975 

900  905  909 1  914  918 

923  927  932  936  941 

976 

945  949'  954  958  963 

967  972 1  9761  981  985 

977 

989  994  998  *003  '007 

*012  »016  '021  '025  *029 

978 

99  034  038:  043 1  047  052 

056'  Oeil  065  069  074 

979 

078  083,  087,  092  096 

100  105|  109,  114  118 

980 

123  127]  131  136  140 

~145  I49  "1541158  l62 

981 

167'  1711  1761  180  185 

l89  "l93  "1981^02  ~207 

4 

982 

211  216  220  224  229 

233  238  242  247  251 

1 

0.4 

983 

255 i  260  264  269  273 

277  282  286 i  291'  295 

2 

0.8 

984 

300  304  3081  313  317 

322  326,  330  335  339 

3 

1.2 

985 

3441  348  352  357  361 

366  370 1  374  379  383 

4 

1.6 

986 

3881  392,  396  401  405 

410  414  419  423  427 

5 

2.0 

987 

432  436  441 i  445  449 

454'  458  463  467  47 l|      6 

2.4 

988 

476 

480  484  489  493 

498  502:  506  511  515 

7 

2.8 

989 

520 

524  528  533  537 

542  546';  550  555  559 

8 
9 

3.2 
3.6 

990 

564 

568;  572,  577 1  581 

~585  ^90  ^94 ,  ^99 1  ~603 

991 

607 

612  616  621  625 

"629  "634  "638  "642  "647 

992 

651 j  6561  660'  664  669 

673  677  682  686  691 

993 

695  6991  704  7081  712 

717,  721 1  726,  730|  734 

994 

739'  743  747  752 1  756 

760  765,  769  774 j  778 

995 

782,  787  791  795'  800 

804  808  813:  817'  822 

996 

826  830  835  839  843 

848  852'  856'  861 1  865 

997 

870  874'  878  883,  887 

891  896  900  904!  909 

998 

9131  9171  922  926  930 

935  939  944  948'  952 

999 

957  961 

965  j  970  974 

978,  983,  987,  991 

99b 

lOM 

00  006 [  004 

~oo9J"ol3  "on 

022  026 

030 

035 

"039 

N. 

L.O 

1 

2 

3 

4 

5 

6 

7 

8 

9 

P.P. 

64 


TRICOXOMETRY 


TRIGONOMETRY 


Plane  Trigonometry  treats  of  the  solution  of  plane  tri- 
angles. In  every  triangle  there  are  six  parts — three  sides 
and  three  angles.  These  parts  are  so  related  that  when 
three  of  the  parts  are  given,  one  being  a  side,  the  other 
parts  may  be  found. 

An  angle  is  measured  by  the  arc  included  between  its 
sides,  the  center  of  the  circumference  being  at  the  vertex 
of  the  angle.  For  the  purpose  of  measuring  angles,  the 
circumference  is  divided  into  360  equal  parts  called  degrees, 
each  degree  being  divided  into  60  equal  parts  called  minutes. 

The  complement  of  an  arc  is  90°  minus  the  arc. 
The  supplement  of  an  arc  is  180°  minus  the  arc. 

In  trigonometry,  instead  of  comparing  the  angles  of 
triangles,  or  the  arcs  that  measure  them,  we  compare  the 
sine,  cosine,  tangent,  cotangent,  secant,  and  cosecant. 

The  sine  of  the  angle  aoc.  Fig.  1, 
f  „      ^s  the  line  a  b  drawn  from  a  per- 

pendicular  to  o  c. 

The  cosine  of  the  angle  a  o  c  is 


B 

c,-"-""^^^ 

a 

C 

b 

Fig.  2 

the  sine  of  its  complement;  or,  it  is  the  distance  ob  i  =  d  a) 
•from  the  foot  of  the  sine  to  the  center  of  the  circle. 

The  tangent  of  the  angle  a  o  c  is  the  line  c  e  that  is  per- 
pendicular to  the  radius  o  c  at  the  extremity  c,  and  which 
is  limited  by  a  line  passing  through  the  center  of  the  circle 
and  the  other  extremity  a. 

The  cotangent  of  the  angle  a  o  c  is  equal  to  the  tangent 
of  its  complement;  or,  it  is  the  line  f  g  perpendicular  to  f  o 
and  limited  by  the  line  o  g  passing  through  the  extremity  a. 


TRIGOXOMETRY  65 

The  secant  of  the  angle  a  o  c  is  a  line  drawn  from  the  center  o 
through  the  extremity  o  and  limited  by  the  tangent  of  the 
same  angle.     Thus,  o  e  \s  the  secant  of  the  angle  ao  c. 

The  cosecant  of, the  angle  is  the  secant  of  the  complement 
of  that  angle.     Thus,  o  g  is  the  cosecant  of  the  angle  a  o  c. 

All  of  these  are  known  as  trigonometric  functions,  and 
are  usually  denoted  by  the  abbreviations  sin,  cos,  tan,  cot, 
sec,  and  cosec. 

The  ratios  existing  between  the  trigonometric  functions 
are  best  explained  by  means  of  a  right  triangle  ABC, 
Fig.  2,  where  C  is  the  right  angle.     They  are  as  follows: 

sin  i4  =-  =  opposite  side  h- hypotenuse 

cos  A=-  =  adjacent  side -^hypotenuse 

tan  A  =  T  =  opposite  side -e- adjacent  side 

cot  A=-  =  adjacent  side -h opposite  side 
a 

sec  A  =-r  =  hypotenuse -H  adjacent  -ide 

cosec  A  =-=hypotenuse -J- opposite  side 
a 

The  hypotenuse  is  the  side  c  opposite  the  right  angle. 
The  adjacent  side  h  is  the  side  that,  with  the  hypotenuse, 
includes  the  angle.  The  opposite  side  a  is  the  side  that  joins 
the  adjacent  side  and  the  hypotenuse. 

From  the  relations  shown,  we  derive  the  following  simple 
principles: 

1 .  The  sine  of  an  arc  equals  the  sine  of  its  supplement,  and 
the  cosine  of  an  arc  equals  the  cosine  of  its  supplement. 

2.  The  tangent  of  an  arc  equals  the  tangent  of  its  supplement, 
and  the  cotangent  of  an  arc  equals  the  cotangent  of  its  supplement. 

3.  The  secant  of  an  arc  equals  the  secant  of  its  supplement, 
and  the  cosecant  equals  the  cosecant  of  its  supplement. 

Thus,  the  sine  of  70°  =  the  sine  of  110° 

the  cosine  of  70°  =  the  cosine  of  110° 

the  tangent  of  70°  =  the  tangent  of  110° 

the  cotangent  of  70°  =  the  cotangent  of  110® 

the  secant  of  70°  =  the  secant  of  110° 

the  cosecant  of  70°  =  the  cosecant  of  110° 


66  TRIGOXOMETRY 

Thus,  if  you  want  to  find  the  sine  of  an  angle  of  120''  30', 
look  for  the  sine  of  180° -120°  30',  or  59°  30'.  etc. 
Functions  of  the  sum  and  difference  of  two  angles: 
sin  (A  +  B)  =  sin  A  cos  B  +  cos  A  sin  B 
cos  {A  +  B)=  cos  A  cos  5  —  sin  A  sin  B 
sin  (A  —  B)=  sin  A  cos  B  —  cos  A  sin  B 
cos  iA-B)=  cos  A  cos  B  +  sin  A  sin  B 
There  are  two  kinds  of  trigonometrical  tables  that  may  be 
used  in  the  computation  of  the  sides  and  angles  of  a  triangle, 
viz. :  natural  sines,  tangents,  etc.,  and  logarithmic  sines,  tangents, 
etc.     Natural  sines,  tangents,  etc.,  are  calculated  for  a  circle 
whose  radius  is  unity,  and  logarithmic  sines,  tangents,  etc.,  are 
calculated  for  a  circle  whose  radius  is  10,000,000,000.     With 
natural  sines,  etc.,  long  and  tedious  operations  in  multiplica- 
tion and  division  are  necessary.     With  logarithmic  sines,  etc., 
these  operations,  in  conjunction  with  a  table  of  logarithms  of 
numbers,  are  reduced  to  simple  addition  and  subtraction. 


ILLUSTRATIONS  OF  TRIGONOMETRY 
APPLIED  IN  PRACTICE 

Example. — Referring  to  Fig.  1.  suppose  that  the  angle  v 
subtended  by  the  lighthouse  is  15°  and  that  the  height  h 
of  the  light  is  144  ft.;  what  is  the  distance  d? 


Solution.- 

Fig.  1 
—In  this  case  we  have 

d        ^            ^^* 

tan  V     tan  15° 

log  144  =  2.15836 
tan  15°  =  9.42805 

log  (f  =  2.73031 
d  =  537.4  ft.     Ans. 

TRIGONOMETRY 


67 


Example. — Referring  to  Fig.  2,  suppose  that  a  ship 
from  C  sails  N  E  by  N,  or  N  33°  45'  E,  a  distance  of  115  mi.; 
how  much  northing  and  how  much  easting  has  she  made? 

Solution. — In  this  case,  A  B  represents  the  easting  and 
C  A  the  northing;  we  have  then, 

AB  =  BCX  sin  33°  45' 
C^=SCXcos33°  45' 
log  115  =  2.06070  log  115  =  2.06070 

sin  33°  45'  =  9.74474  cos  33°  45'  =  9.91985 


log  A  5  =  1.80544  log  C^  =  1.98055 

A  B  =  63.89  mi.     Ans.  C  ^  =  95.6  mi. 

Example. — A  ship  sails  N  69°  E  for  a  distance  of 


Ans. 


and  is  then  found  to  have  made  good  a  course  due  east  and 


Fig.  2 


Fig.  3 


covered  a  distance  of  103  mi.  in  that  direction;  find  the 
direction  and  distance  of  the  current  that  has  acted  on 
the  vessel. 

Solution. — If  N  S,  Fig.  3,  represents  the  meridian,  A  C  iz 
the  course  and  distance  run,  and  A  D  the  course  and  distance 
made  good;  the  line  CD  {  =  A  B)  will  then  represent  the 
direction  and  distance  of  the  current  that  has  acted  on  the 
ship  during  her  run.  Using  natural  functions,  we  find 
the  required  quantities,  the  angle  E  C  D  and  the  distance 


68  NAVIGATION 

CD,  as  follows*  From  the  vertex  C  draw  C  E  perpendicu- 
lar to  A  D,  thus  forming  two  right  triangles  A  E  C  and 
CED.  In  the  triangle  AEC.the  side  d  is  known,  as  is  also 
the  angle  C  A  E.     We  then  have 

C  E  =  dsm  C  A  £  =  80  X  sin  21°  =  80  X  .3583=  28.7 
and  m  =  dcosCA  £  =  80  X  cos  21°  =  80  X  .9336=  74.7 

whence,  n  =  >l  i9-m  =  103-74. 7  =  28.3 

In  the  triangle  CED,  we  have 

tan£CZ;  =  ^  =  |||  =  44°36' 

EC  28.7  28.7     ^- _ 

and  a  = wt^t^^ .  .„  „„-7  =  -v,-^  =  40.3 

cos  EC  D     cos  44°  36'      .712 

Therefore,  C  D  or  the  direction  of  the  current  is  S  44° 

36'  E  and  the  drift  or  distance  40.3  mi,     Ans. 

Note. — For  other  examples   showing  tlT«  application  of  Trigonometry  in 
pr»otice,  see  Navigation  by  Dead  Reckoning. 


NAVIGATION 


THE  COMPASS  ERROR 

TERMS  AND    DEFINITIONS    RELATING   TO    THE   MAG- 
NETIC  NEEDLE 

Magnetism  is  the  name  given  the  phenomenon  displayed 
by  magnets  of  attracting  small  pieces  of  iron  and  steel. 

Magnets  are  of  two  kinds,  natural  and  artificial.     The  ore 
commonly  known  as  lode  stone,  which  possesses  the  property 
of  magnetism,  is  a  natural  magnet.     The  chemical  composi- 
tion of  this  ore  is  about  72  parts  of  iron  and  28  parts  of 
oxygen.     When  a  bar  or  needle  is  rubbed  with  a  piece  of 
lode  stone,  it  acquires  magnetic  properties  similar  to  those  • 
of  the  lode  stone  without  the  latter  losing  any  of  its  own  | 
magnetism.     Such    bars    or    needles    are     called    artificiaJ  j 
magnets. 

Magnetic  Poles. — When  an  ordinary  bar  magnet  is  plunged 
into  iron  filings  it  does  not  become  uniformly  covered 
but  instead  the  filings  arrange  themselves  around  the  end^ 


NAVIGATION  69 

of  the  bar  in  feathery  tufts  that  grow  smaller  as  the  middle 
of  the  bar  is  approached,  leaving  that  portion  bare.  The 
points  around  which  the  filings  concentrate  are  called  the 
poles  of  the  magnet,  while  the  middle  portion  of  the  bar 
which  has  no  visible  magnetic  force  is  called  the  neutral 
zone. 

Magnetic  axis  is  the  line  connecting  the  two  poles  of  a 
magnet. 

Magnetic  Polarity. — A  magnetized  needle  suspended  on 
its  center  of  gravity  will  lay  itself  in  a  definite  direction 
pointing  toward  north  and  south.  This  tendency,  called 
polarity,  applies  to  all  magnets.  The  end  pointing  north- 
wards is  called  the  north-seeking,  or  red,  pole,  and  the 
opposite  the  south-seeking,  or  blue,  pole.  In  other  words, 
the  north-seeking  end  of  the  needle  is  said  to  have  red 
polarity,  while  the  south-pointing  end  has  blue  polarity. 

Magnetic  Attraction  and  Repulsion. — When  two  magnet- 
ized bars,  or  needles,  are  brought  close  together,  the  north- 
seeking,  or  red,  pole  of  one  magnetic  needle  will  repel  the 
north-seeking  end  of  the  other  needle,  while  it  will  attract 
the  south-seeking  end.  From  this,  the  following  law  for 
magnetic  attraction  and  repulsion  may  be  enunciated: 
Poles  of  contrary  names  attract  each  other,  while  poles  of 
the  same  name  repel  each  other;  or,  the  red  pole  of  one 
magnet  will  repel  the  red  of  another,  but  attract  the  blue, 
and  vice  versa. 

Magnetic  Property  of  the  Earth. — The  fact  that  a  suspended 
needle  takes  up  a  fixed  position  has  led  to  the  theory  that 
the  earth  itself  is  a  huge  magnet  having  its  red  and  blue 
magnetic  poles  in  the  neighborhood  of  the  geographical 
poles,  and  that  the  magnetic  needle  turns  to  these  poles 
as  to  the  poles  of  an  ordinary  magnet,  according  to  the  law 
just  given.  Since  the  north-seeking  end  of  a  needle  has 
red  polarity,  it  follows  that  the  magnetic  pole  of  the  earth 
situated  in  the  northern  hemisphere  must  be  a  blue  pole 
and  that  in  the  southern  a  red  pole. 

Magnetic  meridian  is  the  direction  that  the  horizontally 
suspended  magnetic  needle  assumes  when  not  influenced 
by  local  disturbances. 


70  iV.-l  17(7.4  r/O.V 

Magnetic  Components. — The  magnetic  force  of  the  earth 
may  be  resolved  into  two  components,  one  horizontal  and 
one  vertical ;  the  former  represents  the  directive  element  of 
the  compass  needle;  the  latter  acts  only  in  a  vertical  direc- 
tion. A  magnetic  needle  mounted  at  its  center  of  gravity 
would  be  acted  upon  by  both  components. 

Mag^netic  dip  is  the  effect  of  the  vertical  component  of 
the  earth's  magnetic  force,  or  the  inclination,  or  downward 
deflection  from  the  horizontal,  of  a  magnetic  needle  free  to 
move  in  the  vertical  plane.  The  amount  of  dip  varies  from 
0°  to  90°,  being  0°  at  the  magnetic  equator  and  gradually 
increasing  until  90°  is  reached  at  the  magnetic  poles. 

Magnetic  equator  is  a  narrow  belt  or  zone  embracing  all 
points  on  the  earth's  surface  where  the  magnetic  dip  is 
zero;  it  encircles  the  equatorial  part  of  the  earth  and  inter- 
sects it,  but  never  recedes  more  than  16°  on  either  side  of  the 
geographical  equator. 

Magnetic  induction  is  the  property  of  a  magnet  imparting 
magnetism  to  a  body  of  iron  or  steel  in  its  immediate  vicinity. 
Thus,  the  earth  being  a  magnet  will  impart  or  communicate 
magnetism  to  the  hull  of  an  iron  vessel.  The  vessel  is  then 
said  to  be  magnetized  by  induction. 

Magnetic  variation  is  the  angle  that  the  magnetic  meridian 
makes  with  the  geographical  meridian,  or,  what  is  the  same, 
the  angle  that  the  direction  of  the  suspended  needle  makes 
with  the  true  meridian;  it  is  caused  by  the  magnetic  poles 
of  the  earth  not  coinciding  with  the  geographic  poles. 
Variation  is  not  constant,  but  undergoes  a  progressive 
change,  the  annual  amount  of  which  is  invariably  marked 
on  charts. 

Isogenic  lines  are  curves  or  lines  connecting  points  of 
equal  variation.  Charts  on  which  such  lines  are  plotted 
are  called  isogenic,  or  variation,  charts. 

Agonic  lines  are  curves  or  lines  connecting  all  places  on 
the  earth's  surface  where  the  variation  of  the  compass  is 
zero. 

Isoclinic  lines  are  curves  or  lines  that  are  drawn  inter- 
mediate to  the  poles  and  equator  connecting  all  places 
where  the  dip  of  the  magnetic  needle  is  the  same. 


NAVIGATION 


N 


Isodynamic  lines  are  curves  or  lines  connecting  all  places 
where  the  intensity  of  the  earth's  magnetic  force  is  the  same. 

Deviation. — A    compass    placed    on    board     an    iron    or 
steel  vessel  is  subjected  to  various  disturbances  from  the 
magnetism  of  the  surrounding  metal,  and  the  errors  thus 
produced  are   collectively   known   as  the   deviation   of   the 
compass.     Deviation  may  also  be  defined  as  the  deflection 
of  the   compass  needle   from   the   magnetic   meridian.     At 
the  same  time,  the  needle  is  acted  upon  by  variation  and  the 
combined  eflfect  of  the  two  may  properly  be  termed  the 
total  error  of  the  compass.     Deviation  and  variation  must  not 
be   confounded  with 
one   another;    varia-    Jffaff 
tion,  being  caused  by 
the  magnetic  force  of 
the  earth,  affects  the 
compass  alike  on  all 
courses,  while  devia- 
tion, being  caused  by 
the  magnetism  of  the 
iron  in  the  hull  and 
fittings  of  the  vessel 
itself,  varies   for  dif- 
ferent headings  of  the 
ship.     The    reason 
why  deviation  varies 
as  indicated  will  be 
readily  understood 

by  remembering  that,  through  induction  of  magnetism  from 
the  earth,  any  iron  or  steel  vessel  may  be  considered  as  a 
large  magnet  having  red  and  blue  polarity  that  affects 
the  compass  needle  in  exactly  the  same  manner  as  an  ordinary 
magnet.  Suppose  that  the  vessel  has  blue  polarity  in  the 
bow  and  red  polarity  in  the  stern  and  that  no  other  magnetic 
disturbances  have  any  effect  on  the  compass  needle;  then, 
when  heading  in  the  direction  of  the  magnetic  meridian, 
as  (a)  in  the  appended  figure,  it  is  evident  there  will  be  no 
deflection  of  the  needle.  But  when  turning  the  bow  in  any 
other  direction,  for  example  to  east,   as  in   (6),  there  will 


(3 


rw 


Caj 


72  NAVIGATION 

necessarily  be  a  deflection  due  to  the  influence  of  the  altered 
position  of  the  ship's  magnetic  poles.  Hence,  the  cause 
of  the  deviation  being  different  for  different  positions  of 
the  ship's  head. 

Subpermanent  magnetism  is  the  magnetic  condition  of 
a  more  or  less  enduring  character  possessed  by  a  ship  when 
launched  and  which  was  acquired  when  building,  by  induc- 
tion from  the  earth  and  rendered  permanent,  or  nearly  so, 
by  hammering. 

Retentive  magnetism  is  the  temporary  magnetism  com- 
municated to  an  iron  ship  when  her  head  is  kept  in  one 
direction  for  some  time;  as,  for  example,  when  moored  to 
a  pier,  or  when  steering  a  continuous  course  for  several 
days.  Retentive  magnetism  frequently  remains  for  days 
after  the  cause  is  removed. 

Semicircular  deviation  is  the  effect  of  the  combined  action 
of  the  subpermanent  magnetism  and  the  transient  magnet- 
ism from  the  vertical  soft  iron  of  the  ship.  It  is  called 
semicircular  because  it  has  the  contrary  name  and  maximum 
value  in  opposite  semicircles. 

Quadrantal  deviation  is  the  deviation  produced  by  the 
transient  magnetism  of  horizontal  soft  iron.  It  is  called 
quadrantal  because  it  is  greatest  on  the  quadrantal  points, 
and  because  it  changes  its  name  in  each  successive  quadrant. 

Soft  Iron  is  iron  that  becomes  magnetized  as  soon  as  it 
is  exposed  to  the  influence  of  some  magnetic  body  but 
which  has  not  power  to  retain  the  magnetism  thus  acquired. 
Malleable  and  cast  iron  belong  to  this  class. 

Hard  Iron  is  iron  combined  with  a  certain  percentage  of 
carbon  (steel)  and  which  has  the  property  of  retaining  its 
magnetism  permanently,  or  nearly  so,  when  magnetized. 

Vertical  and  horizontal  iron  refer  to  the  structure  of  a 
vessel  built  of  iron  or  steel  To  the  first  named,  belongs 
all  iron  running  in  a  vertical  direction,  such  as  frames,  stan- 
chions, bulkheads,  etc.;  to  the  latter,  all  iron  running  hori- 
zontally, such  as  the  keel,  deck  beams,  deck  plates,  etc. 

Local  attraction  is  any  disturbance,  temporary  or  other- 
wise, caused  by  any  iron,  steel,  dynamo,  electric  wiring, 
etc.,  in  the  immediate  vicinity  of  the  compass  and  which 


NAVIGATION 


73 


is  not  included  in  the  stationar/  metal  surrounding  the 
compass.  In  this  expression  is  included  also  the  magnetic 
influences  due  to  the  locality  in  which  the  ship  happens  to 
be,  for  example,  when  in  dock  alongside  of  iron  ships,  cranes, 
pillars,  etc.,  or  when  in  close  proximity  to  iron-bearing 
mountains  or  volcanic  islands.  The  effect  on  the  compass 
of  cargo  containing  iron,  such  as  iron  ore,  machinery,  etc., 
may  also  be  classed  as  local  attraction. 

COMPENSATION  OF  COMPASSES 

The  general  principle  of  compensating  a  compass  is  to 
counteract  the  magnetic  disturbances  by  means  of  magnets 
and  soft  iron  placed  in  the  immediate  neighborhood  of  the 
compass  and  in  such  position  as  to  cause  a  disturbance 
contrary  to  that  caused  by  the  iron  of  the  ship.  The  mag- 
netic needle  will  thus  be  left  comparatively  free.  This 
may  be  illustrated 
as  follows:  Bear- 
ing in  mind  that 
the  north  -  seeking 
end  of  the  compass  rimi 
needle  always  pos- 
sesses red  polarity 
and  that  red  polar- 
ity repels  red  and 
attracts  blue,  and 
vice  versa,  assume 
a  needle  to  be  de- 
flected from  mag- 
netic north  A'  to  n. 
Fig.  1.  Then,  in 
order  to  bring  the  needle  back  to  its  proper  position  N,  or, 
what  is  the  same  thing,  to  counteract  the  effect  of  the  sur- 
rounding iron  and  steel,  magnets  may  be  placed  in  any  of  the 
positions  shown  at  a  suitable  distance  from  the  needle.  It 
will  be  noticed  in  each  case,  that  is,  if  the  magnets  are  used 
singly  or  in  pairs,  or  in  any  other  combination,  that  the 
whole  operation  of  compensating  is  simply  an  application 
of  the  law  of  magnetic  attraction  and  repulsion. 


74 


NAVIGATION 


The  two  principal  errors  of  a  compass  to  compensate  are 
the  semicircular  deviation  and  the  quadrantal  deviation. 
The  semicircular  error  is  the  combined  effect  of  subper- 
manent  magnetism  of  the  ship  and  the  induced  magnetism 
of  vertical  iron;  but,  as  a  whole  and  for  the  purpose  of 
compensation,  it  is  convenient  to  divide  this  error  into  two 
parts  and  consider  each  part  as  a  separate  force,  one  acting 
in  a  fore-and-aft,  and  the  other  in  an  athwartship  direction. 
The  first  part  of  that  error,  which  affects  the  compass 
needle  when  heading  on  easterly  and  westerly  courses,  is 
usually  denoted  by  the  letter  i5;  while  the  second  part,  which 
affects  the  needle  when  heading  on  northerly  and  southerly 
courses,  is  denoted  by  the  letter  C.  The  quadrantal  deviation, 
resulting  from  horizontal  iron  and  which  attains  its  maxi- 
mum value  when  the  ship  is  heading  on  any  of  the  quadrantal 
points,  is  denoted  by  D.  These  forces  B,  C,  and  D  are 
technically  known  as  coefficients. 

When  compensating  a  compass,  it  has  been  found  good 
practice  to  correct  the  quadrantal  deviation  first  and  then 

the  two   parts   of  the 
^  ^^    semicircular  error. 

To  Compensate  the 
Quadrantal  Deviation. 
Since  this  error  which 
is  caused  by  the  mag- 
netism of  horizontal  soft 
iron,  attains  its  maxi- 
mum value  on  the  quad- 
rantal points,  the  ship  is 
swung  in  the  direction  of 
one  of  these  points,  for 
example,  N  E,  as  shown 
in  Fig.  2;  and  since  the 
error  is  caused  by  soft 
iron,  it  is  necessary  to 
compensate  it  by  using  hollow  soft-iron  spheres.  These 
spheres  are  so  placed  in  the  plane  of  the  compass  card  as  to 
cause  an  opposite  effect  to  the  magnetism  of  horizontal  iron. 
The  error  to  be  corrected  being  easterly  in  the  N  E  and  S  W 


NAVIGATION 


75 


quadrants  and  westerly  in  the  N  W  and  S  E  quadrants  in 
almost  every  ship,  the  spheres  are  placed  athwartship  on  the 
same  horizontal  plane  and  at  equal  distances  from  the  cen- 
ter of  the  compass,  the  distance  being  determined  by  trial, 
moving  them  to  and  fro  in  their  respective,  slits  until  the  com- 
pass shows  the  correct  quadrantal  point  on  which  the  ship  is 
headed.  The  quadrantal  deviation  is  constant  in  all  lati- 
tudes, provided  that  the  surrounding  iron  remains  in  the 
same  position,  and  hence  its  compensation  remains  constant 
everywhere. 

To  Compensate  Coefficient  C. — Swing  the  ship's  head 
toward  magnetic  north,  according  to  some  compass  not 
influenced  by  the  magnetism  of  the  ship  (for  instance  by  a 
compass  on  shore),  or,  better  still,  by  permanent  marks  on 
land,  the  bearing  be- 
tween which  coincides 
with  the  magnetic  me- 
ridian. If  the  compass 
in  -^his  position  does  not 
show  exactly  north,  but 
is  deflected  to  the  east, 
as  shown  in  Fig.  3,  place 
a  magnet  on  the  fore- 
and-aft  line  with  its  red 
pole  to  starboard. 

The  distance  of  the 
magnet  must  be  deter- 
mined by  trial;  begin  by 
placing  the  magnet  at 
some  distance  from  the 
compass  and  gradually 
approach  it  until  the 
compass  shows  correct 
magnetic  north,  when  the  magnet  is  secured  to  the  deck. 
If  the  needle  had  been  deflected  to  the  west,  it  is  evident 
that  the  red  end,  or  pole,  of  the  magnet  should  have  been 
placed  to  the  port  side.  In  case  this  error  is  large,  the  ship 
is  swung  toward  magnetic  south  and  a  similar  operation 
is  performed  on  that  heading. 


Cbmpensalion 

ofC. 


Fig.  3 


76 


NAVIGATION 


lo  Compensate  Coefficient  B. — --The  ship  is  swung  magnetic 
east  or  %vest.  If  swung  to  east  and  the  compass  north  on  that 
heading  is  deflected  to  the  west,  as  in  Fig.  4,  place  a  magnet 
on  the  athwartship  line  with  its  blue  pole  forwards  and  at  a 
distance  from  the .  compass  sufficient  to  correct  the  error. 
The  compass  north  being  deflected  to  the  east,  the  compen- 
sating magnet  is  reversed.  A  similar  operation  is  then  per- 
formed, if  necessary,  with  the  ship's  head  swung  west. 

The  foregoing  applies  to  ships  not  equipped  with  a  com- 
pensating binnacle.  It  becomes  necessary  then  to  have 
fore-and-aft  and  athwartship  lines  run  out  on  the  deck  and 


Compen^aiion  of  B, 

Fig.  4 


intersecting  at  a  point  vertically  below  the  center  of  the 
compass  to  be  compensated.  The  magnets  are  then  placed 
perpendicularly  with  their  centers  on  these  lines,  as  shown 
in  Figs.  3  and  4. 

At  present,  however,  and  particularly  in  iron  ships,  com- 
pensating magnets  are  seldom,  if  ever,  fastened  to  the  deck, 
but  are  fitted  to  slide  into  horizontal  fore-and-aft  and 
athwartship  receptacles  within  the  binnacle.  In  most 
binnacles,  the  receptacles  are  arranged  in  such  a  manner 
as  to  be  moved  up  or  down,  nearer  to,  or  farther  from,  the 
compass,  as  may  be  required,  and  then  secured  by  means 


NAVIGATION  11 

of  clamp  screws  that  cannot  be  touched  except  by  opening 
the  door  of  the  binnacle;  in  others,  the  movement  of  the 
magnets  is  controlled  from  the  outside  of  the  binnacle  by 
means  of  a  crank-key,  thus  enabling  the  adjuster  to  watch 
the  compass  while  he  is  altering  the  position  of  the  magnets, 
and  to  move  them  the  exact  amount  required;  after  the 
adjustment  is  completed,  the  crank-key  is  removed  and  the 
casing  locked,  making  it  impossible  for  any  one  to  tamper 
with  the  magnets.  The  principle  of  magnets  being  stored 
within  the  binnacle  is  precisely  the  same  as  in  securing  them 
to  the  deck,  both  the  magnets  for  B  and  C  being  exactly 
parallel  to  the  ship's  deck  or  to  the  plane  of  the  compass 
card  when  the  ship  is  in  an  upright  position. 

As  previously  stated,  the  compensation  of  the  quadrantal 
error  is  good  for  all  latitudes.  Such,  however,  is  not  the 
case  with  that  part  of  the  semicircular  error  caused  by  the 
induced  magnetism  of  vertical  iron.  Since  the  amount  of 
this  magnetism  depends  on  the  magnetic  dip,  it  is  evident 
that  the  deviation  resulting  from  it  will  depend  on  the 
magnetic  dip  also.  To  distinguish  this  latter  error  from 
that  produced  by  subpermanent  magnetism  and  to  apply 
to  it  a  proper  compensation  is  a  difficult  task,  requiring 
skill,  good  judgment,  and  an  intimate  knowledge  of  the 
magnetic  condition  of  the  ship.  The  usual  method  of  cor- 
recting or  compensating  this  error  is  by  means  of  a  vertical 
iron  bar,  called  the  Flinders  bar,  which  is  placed  within  or 
outside  the  binnacle  either  immediately  before  or  abaft  the 
compass.  This  bar,  which  received  its  name  from  its  inventor, 
Captain  Flinders,  of  the  British  Navy,  is  not  a  permanent 
magnet;  it  is  made  of  soft  iron,  and  consequently  receives 
its  magnetism  by  induction  from  the  earth. 

The  object,  therefore,  to  be  attained  by  the  Flinders  bar 
is  to  place  it  in  such  a  position  within  the  binnacle  that  the 
gradual  change  of  its  magnetism,  produced  by  the  change 
in  latitude,  will  counterbalance  the  effect  of  the  likewise 
varying  magnetism  of  the  vertical  iron  of  the  ship. 

Heeling  Error. — When,  from  some  cause,  the  ship  has  a 
list  to  either  side,  a  new  error  is  created,  which  is  generally 
known  as  the  heeling  error.     The  principal   cause   of  this 


78  NAVIGATION 

error  may  be  explained  as  follows:  When  the  ship  heels 
over  from  the  pressure  of  wind,  shifting  of  cargo,  or  unequal 
trimming  of  coal  bunkers,  all  horizontal  iron,  such  as  the 
deck  beams,  tends  to  assume  a  vertical  position,  and  in 
doing  so  will  receive  magnetism  by  induction  from  the  earth. 
Thus,  for  a  ship  in  the  northern  hemisphere,  the  upper  ends 
of  the  beams,  whether  heeling  to  port  or  starboard,  will 
acquire  blue  polarity  and  the  lower  ends  red  polarity.  In 
the  southern  hemisphere,  these  conditions  are  reversed. 
As  a  consequence,  the  north  end  of  the  compass  needle  will 
be  attracted  by  the  upper  ends  of  the  beams  in  north  mag- 
netic latitudes  and  repelled  in  south  magnetic  latitudes,  and 
the  amount  of  this  error  will  evidently  depend  on  the  extent 
of  heeling.  As  a  general  rule,  the  heeling  error  is  greatest 
on  northerly  and  southerly  courses  and  least  on  easterly 
and  westerly  courses.  The  simplest  method  of  compensa- 
ting the  heeling  error  is  to  place  a  magnet  vertically  below 
the  center  of  the  compass  bowl.  Before  compensating,  the 
ship  is  swung  into  a  north-and-south  direction  and  heeled 
over  at  least  5°,  for  instance,  to  starboard.  If  in  this  posi- 
tion the  compass  north  is  deflected  toward  the  uppermost 
or  windward  side  (as  is  usually  the  case),  the  compensating 
magnet  is  placed  with  its  red  pole  uppermost,  and  at  a  dis- 
tance from  the  compass  bowl  that  is  determined  by  raising 
or  lowering  the  magnet  until  the  compass  points  correctly. 
In  the  very  exceptional  case  of  the  needle  being  deflected 
toward  the  lower  or  leeward  side,  the  blue  pole  of  the  mag- 
net is  placed  uppermost. 

The  compensation  for  heeling  error  is  good  only  for  the 
latitude  in  which  it  is  made,  and  it  therefore  becomes  a 
necessity  to  renew  it  when  the  ship  has  changed  her  latitude 
considerably,  usually  for  every  change  of  10°  in  latitude. 
At  the  magnetic  equator,  the  error  is  at  its  minimum;  and 
when  entering  the  southern  hemisphere,  it  again  increases 
in  amount,  although  of  a  different  character;  in  southern 
magnetic  latitudes,  therefore,  the  vertical  magnet  will  have 
to  be  reversed. 

The  foregoing  remarks  on  compensation  are  general,  and 
while   the  operations  may  appear  easy  of  execution,  they 


NAVIGATION  79 

nevertheless  require  a  certain  amount  of  skill  and  experi- 
ence to  meet  all  conditions  that  may  arise;  and  for  this 
reason  it  is  advisable  always  to  employ  a  professional  com- 
pass adjuster,  the  cost  of  this  being  insignificant  when  com- 
pared with  the  importance  of  the  subject. 

SWINGING  A  SHIP  FOR  DEVIATION 

Preparatory  to  swinging  a  ship  for  finding  the  amount  of 
deviation  remaining  after  the  compass  is  compensated,  a 
well-defined  distant  object  on  land  should  be  selected,  the 
correct  magnetic  bearing  of  which  is  known.  If  the  ship's 
position  is  accurately  fixed,  the  magnetic  bearing  of  the 
selected  object  may  be  taken  directly  from  the  chart;  or, 
it  may  be  conveniently  found  by  taking  the  mean  of  all 
compass  bearings  of  the  object  after  the  ship  is  swung. 
Regularly  established  ranges,  such  as  are  found  in  the  princi- 
pal ports,  are,  however,  to  be  preferred  whenever  available. 

The  magnetic  bearing  of  the  object  being  determined, 
the  ship  is  gradually  swung  round  so  as  to  bring  her  head 
successively  upon  each  of  the  32  points  of  the  standard 
compass,  steadying  at  each.  The  difference  between  the 
•correct  magnetic  bearing  of  the  object  and  the  successive 
bearings,  as  observed  with  the  compass  on  board  v/hen  the 
ship's  head  is  on  the  several  points,  will  show  the  error  on 
each  of  these  points,  or,  in  other  words,  the  deviation  of 
the  standard  compass  according  to  the  direction  in  which 
the  ship's  head  was  placed. 

When  no  suitable  object  by  which  a  range  may  be  estab- 
lished is  in  sight,  the  deviation  may  be  found  by  what  is 
known  as  simultaneous  reciprocal  bearings.  This  method 
consists  of  a  compass  being  brought  on  shore  and  placed  on 
a  tripod  in  ^  carefully  selected  spot,  where  it  will  be  free 
from  the  magnetic  influence  of  any  iron  and  where  its  loca- 
tion can  be  distinctly  seen  from  the  standard  compass  on 
board.  As  the  ship  is  swung  around,  with  her  head  suc- 
cessively upon  each  of  the  32  points  of  the  standard  com- 
pass, simultaneous  observations,  or  bearings,  are  taken  by 
the  observer  stat'oned  at  each  compass,  according  to  some 
prearranged  signals. 


80 


NAVIGATION 


The  bearings  should  be  strictly  simultaneous,  and  in  order 
to  guard  against  any  mistake  regarding  the  exact  instant  at 
which  bearings  are  taken,  both  observers  should  note  the 
time  of  each  observation  by  watches  previously  compared. 
To  obtain  the  deviation  resulting  from  observations  by  this 
method,  the  bearings  taken  by  the  shore  compass  must  be 
reversed  and  considered  as  correct  magnetic.  The  rule  to  be 
followed  in  naming  the  deviation  when  comparing  bearings  is: 

Rule. — //  the  correct  magnetic  bearing  lies  to  the  right  of 
the  compass  bearing,  the  deviation  is  easterly;  if  to  the  left, 
the  deviation  is  westerly. 

Illustration. — Referring  to  the  figure^  suppose  that  when 
the  vessel  is  heading  W  by  N  the  shore  compass  bears  E  N  E 
and  that  the  bearing  of  the  ship  by  shore  compass  (taken 
at  the  same  time)  is  W  by  S.     W  by  S  reversed  is  E  by  N, 


E 


Fig.  5 


which  is  the  correct  magnetic  bearing.  The  difference 
between  this  and  the  compass  bearing  is  one  point.  Hence, 
the  deviation  for  the  heading  W  by  N  is  one  point,  or 
11°  15'  east,  because  the  magnetic  bearing  falls  to  the  right 
of  the  compass  bearing,  as  shown  in  Fig.  5. 

The  deviation  determined  ,by  either  method  belongs,  of 
C'Durse,  only  to  the  compass  by  which  the  observations  are 
made,  and  is  not  applicable  to  that  compass  if  removed  or 
rilaced  in  some  other  position  on  the  ship. 

When  deviations  are  small,  as  is  usually  the  case  in  ships 
where  compasses  are  carefully  adjusted,  it  is  sufficient  to 


NAVIGATION 


81 


determine  the  deviation  for  the  eight  principal  points  only, 
and  then  find  the  deviation  for  intermediate  points  by 
means  of  the  various  diagrams  in  use. 

The  following  forms  will  be  found  convenient  for  tabulating 
bearings  and  the  resulting  deviations. 


BEARINGS  OF  A  DISTANT  OB 

JECT 

Ship's 

Head 

by 

Standard 

Compass 

Bearing  of 
Distant 

Obiect  by 
Standard 
Compass 

Bearing 

Referred 

to 

East  Point 

Deviation 

of 
Standard 
Compass 

N 
NE 

E 
SE 

S 
S  W 

W 
N  W 

N41°E 
N30°E 
N  11°  E 
N  12°  W 
N33°  W 
N27°  W 

N 
N  28°  E 

E    49°  X 
E    60°  N 
E     79°  N 
E  102°  N 
E  123°  N 
E  li7°  N 
E    90°  N 
E    62°  N 

36°  15'  W 
25°  15'  W 

6°  15' W 
16°  45'  E 
37°  45'  E 
31°45'E 

4°  45'  E 
23°  15'  W 

682 


Sum  =  682°- 

E   85.25°    N  =  E   85°    15'    N 


Corr.    magnetic   bearing  = 
=  N4°45'E 

When  bearings  have  different  names,  or  do  not  lie  in  the 
same  quadrant,  it  is  advisable  always  to  refer  them  to  some 
convenient  cardinal  point,  as  shown. .  This  will  prevent  any 
mistake  in  finding  the  mean  or  correct  magnetic  bearing  of 
the  object. 

Remarks  on  Compass  Management. — The  accuracy  of 
deviation  tables  should  be  tested  whenever  practicable,  or 
whenever  there  is  reason  to  believe  a  change  of  the  magnetic 
condition  of  the  ship  has  taken  place.  After  coming  out  of 
dry  dock,  after  target  practice,  after  considerable  altera- 
tions in  the  fittings  of  the  vessel,  and  after  taking  in  or 
unloading  some  cargo  of  a  magnetic  character,  such  as 
machinery,  iron  ore,  etc.,  a  new  deviation  table  should  be 
made  in  case  the  given  values  do  not  conform  with  actual 


82 


NAVIGATION 


conditions.  A  navigator  should  ever  be  watchfvxl  about 
the  proper  performance  of  the  compass,  and  particularly  so 
in  modem  steamships,  where  new  forms  of  disturbances  are 
likely  to  appear  at  any  time.  The  principal  cause  of  the 
directive  force  of  a  magnetic  needle  being  lessened  are  vibra- 
tions. If  the  compass  is  exposed  or  subjected  to  vibrations 
from  the  propeller  or  engine  room  for  any  length  of  time, 
it  will  begin  to  act  sluggishly,  and  the  needles  will  have  to  be 
recharged  or  remagnetized. 

V^'.th   the   introduction   of  electricity   on  board  ships,   a 
new  form  of  compass  disturbances  has  been  created,  inas- 

RECIPROCAL  BEARINGS 


Ship's 
Head  by 

the 
Standard 
Compass 

Simultaneous  Bearings 

Deviation 

Time 

By  the 
Standard 
Compass 

By  the 

Shore 

Compass 

(Reversed) 

of 
Standard 
Compass 

7h  56m 
7h59m 
8h    3m 
8h    5m 

8h    8m 

North 
NbvE 

N  N  E 

N  Eby  N 

NE 

S  25.3°  E 
S  30  9°  E 
S  35.2°  E 
S  38.7°  E 
S  40.8°  E 

S  30.8°  E 
S  32.5°  E 
S  34.3°  E 
S  35.4°  E 
S  36.3°  E 

5.5°  W 

1.6°  W 

.9°  E 

3.3°  E 

4.5°  E 

much  as  the  magnetisrti  of  the  large  electromagnets  used  in 
the  dynamos  and  the  electric  currents  in  general  may  dis- 
turb a  compass  at  a  considerable  distance.  The  committee 
of  Lloyd's  Register  of  British  and  Foreign  Shipping  has 
made  the  following  suggestions  in  reference  to  protecting 
compasses  from  the  influence  of  electricity  on  shipboard: 

1,  That  dynamos  and  *Jectric  motors  should  be  placed 
as  far  as  possible  from  all  compasses  and  at  a  distance,  of 
at  least  30  ft.  from  the  standard  compass. 

2.  That  wires  conducting  electric  currents  should  not 
come  nearer  than  16  ft.  to  any  compass,  whereas  wires  con- 
ducting strong  currents  should  be  at  a  still  greater  distance. 


NAVIGATION  83 

3.  That  the  compensating  of  compasses  should  be  done 
when  the  dynamos  are  at  rest,  while  the  operations  for 
determining  the  deviation  should  be  performed  when  the 
dynamos  are  running. 

CORRECTION  OF  COURSES 

Compass  course  is  the  course  steered  by  a  ship.  It  may 
be  affected  by  variation,  deviation,  and  leeway;  and  in 
order  to  find  the  corresponding  true  course  proper  allowance 
must  be  made  for  any  or  all  of  these  errors. 

True  course  is  equal  to  the  compass  course  corrected  for 
variation,  deviation,  and  leeway;  or,  it  is  the  angle  that 
the  ship's  track  over  ground  makes  with  the  true,  or  geo- 
graphical, meridian. 

Leeway  is  the  result  of  the  pressure  that- the  sea  or  wind 
exerts  on  the  hull  and  sails  of  a  ship,  causing  her  to  drift 
sideways.  The  amount  of  leeway  varies  with  the  strength 
of  wind,  form  of  hull  under  water,  etc.  It  is  usually  esti- 
mated by  eye,  the  observer  being  guided  by  the  angle 
between  the  ship's  wake  and  fore-and-aft  line,  and  is 
expressed  in  points  and  fractions  of  a  point. 

To  find  the  true  course  from  a  given  compass  course  apply 
easterly  variation  and  deviation  to  the  right,  and  westerly 
variation  and  deviation  to  the  left.  Allow  leeway  in  direc- 
tion toward  which  the  wind  is  blowing. 

Example. — Compass  course  is  S  W  by  W  ^  W,  deviation 
14°  W,  variation  20°  E,  wind  S  S  E,  leeway  2i  points; 
find  the  true  course. 

Solution. —  Comp.  course  =  S  W  by  W  i  W 

Leeway  (to  the  right)  =2}  points 

Course  through  water  =  W  ^  S 

or  =  S  84°  22'  W 
Dev.=     14°    O'W 


Mag.  course  =  S  70°  22'  W 
Var.  =     20°    0'  E 


True  course  =  S  90°  22'  W 
or  =  west.     Ans. 


84  NAVIGATION 

Example. — Compass  course  S  E  by  S,  deviation  11°  E, 
variation  25°  W,  wind  S  W  by  S,  leeway  i  point;  required 
the  true  course. 

Solution. —  Comp.  course  =  S  E  by  S 

Leeway  (to  the  left)  =  i  point 
Course  through  water  =  S  E  f  S 

or  =  S36°34'  E 
Dev.=     11°    0'  E* 
Mag.  course  =  S  25°  34'  E 
Var.  =     25°    0'  W 


True  course  =  S  50°  34'  E 

or  =  S51°    0' E.     Ans. 
To   find   the   compass   course    from   a   given   true   course 

apply  westerly  variation  and  deviation  to  the  right,  and 
easterly  variation  and  deviation  to  the  left.  If  leeway, 
apply  against  the  wind. 

Example. — Required   the    compass   course,    having  given 
true  course  N  8°  W,  variation  17°  10'  W,  deviation  3°  20'  E; 
the  wind   is  easterly  and  the   leeway  estimated  to  -J  point. 
Solution. — 

True  course  =  N    8°    0'  W 

Var.=      17°  10' W 

Mag.  course  =  N    9°  10' E 

Dev.  =        3°  20'  E 


N    5°  50'  E 
Leeway  h  point  =        5°  37'     (against  the  wind) 
Comp.  course  =  N  11°  27'  E 

or  =  N  by  E,  nearly.     Ans. 
iLxam pic- -The  true  course  to  a  certain  point  is  N  30°  E, 
the   variation  is  28°  W,    deviation  6°  E;   find  what   course 
to  steer  b\-  the  compass. 
Solution. — 

True  course  =  N  30°  E 
Var.  =      28°  W 


Mag.    course  =  N  58°  E 
Dev.  =        6°  E 


Comp.  course  =  N  52°  E.     Ans. 


NAVIGATIO.y 


85 


In  correcting  courses,  it  is  well  to  bear  in  mind  that, 
since  the  compass  card  is  the  representation  of  the  visible 
horizon,  the  position  of  the  observer  is  considered  to  be 
at  the  center  of  the  compass  card.  Hence,  when  applying 
corrections,  whether  to  right  or  left,  always  consider  yourself 


to  be  stationed  at  the  center  of  the   card  and  looking  in 
the  direction  of  the  course  to  be  corrected. 

In  the  above  figure,  representing  a  compass  card,  quarter- 
points  are  indicated  by  small  triangles,  and  half-points  by 
elongated  diamonds;  each  subdivision  is  designated  by  refer- 
ence to  the  compass  points  between  which  they  are  situated, 
as  shown  in  the  following  tables. 


86 


NAVIGATION 


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1 

C 

1 

e 

T.  quarto  G. 

G.  T. 
G.  quarto  T. 

Greco. 
G.  quarto  L. 

G.  L. 
L.  quarto  G. 

c 
> 

L.  quarto  S. 

S.  L. 
S.  quarto  L. 

Scirocco 
S.  quarto  O. 

O.  S. 
O.  quarto  S. 

C/3 

13 
1 

.    .  ^     d    .   . 
o  o  -    ■  =  O  2 

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6 

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ddo^o^^ 

c 

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CO 

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i^  w  "C    .  "B  w  '^' 

2;      ^'      z      w 

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w 

W        W        CO        w 

"^  w  •§    .  u  cii  ^ 
o     .    rt  H    cfl  ^    o 

.  t  CO    P      .    g  CO    t 
rt     .    ^  CO    "     .    rt 

S  w  w      w  ^  g 

W          CO          CO          CO 

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NAVIGATION 


89 


c 

.5 

Ostro. 
O.  quarto  L. 

O.  L. 
L.  quarto  O. 

Libeccio 
L.  quarto  P. 

P.  L. 
P.  quarto  L. 

Ponente. 
P.  quarto  M. 

P.  M. 
M.  quarto  P, 

Maestro. 
M.  quarto  T. 

M.  T. 
T.  quarto  M. 

1 

Syd. 

S.  till  W. 

S.  S.  W. 

S.  W.  till  S. 

S.  W. 
S.  W.  till  W. 

w.  s.  w. 

W.  till  s. 

West 

W.  till  N. 

W.  N.  W. 

N.  W.  till  W. 

N.  W. 

N.  W.  till  N. 

N.  N.  W. 

N.  till  W. 

C/2 

Sur. 
S.  cuarto  S.  O. 

S.  S.  O. 
S.  O.  cuarto  S. 

S.O. 
S.  O.  cuarto  0. 

O.S.  O. 
O.  cuarto  S.  0. 

Oeste. 
O.  cuarto  N.  0. 

O.  N.  O. 
N.  0.  cuarto  O. 

N.  O. 
N.  O.  cuarto  N. 

N.  N.  O. 
N.  cuarto  N.  O. 

C 

o 

Sud. 

S.  zu  W. 

S.  S.  W. 

S.  W.  zu  S. 

S.  W. 

S.  W.  zu  W. 

W.  S.  W. 

W.  zu  S. 

West 

W.  zu  N. 

W.  N.  W. 

N.  W.  zu  W. 

N.  W. 

N.  W.  zu  N. 

N.  N.  W. 

N.  zu  W. 

XI 

Sud. 
S.  quart  S.  O. 

S.  S.  0. 
S.  O.  quart  S. 

S.O. 
S.  0.  quart  0. 

0.  S.  O. 
0.  quart  S.  0. 

Ouest. 
0.  quart  N.  O. 

O.  N.  O. 
N.  O.  quart  O. 

N.  O. 
N.  O.  quart  N. 

N.  N.  0. 
N.  quart  N.  0. 

1 

C 

South 

Sby  W 

SS  W 

S  WbyS 

SW 

SWby  W 

WS  W 

WbyS 

West 

Wby  N 

W  N  W 

NWby  W 

N  W 

N  Wby  N 

N  N  W 

Nby  W 

90  NAVIGATION 

THE  USE  OF  PELORUS  IN  HEADING  A  SHIP  IN  ANY 
DESIRED  MAGNETIC   DIRECTION 

On  the  date  of  observation,  select,  beforehand,  a  suitable 
hour  of  local  apparent  time,  and  estimate  also,  in  advance, 
by  dead  reckoning,  the  position  of  the  ship  for  the  hour 
in  which  the  observation  is  to  be  made.  With  the  latitude  of 
the  position  thus  found  and  the  declination,  enter  the  azimuth 
tables  and  find  the  true  azimuth  or  bearing  of  the  sun 
for  the  selected  hour  of  apparent  time;  apply  to  this  true 
azimuth  the  variation  of  the  locality  taken  from  the  chart; 
the  result  will  be  the  magnetic  bearing  of  the  sun  for  the  time 
selected.  Shortly  before  the  time  selected,  and  when  the 
ship  has  reached  the  position  decided  on,  set  that  point  of  the 
pelorus  corresponding  with  the  required  magnetic  direction  to 
the  ship's  head  and  turn  the  sight  vanes  of  the  instrument 
to  correspond  with  the  magnetic  bearing  of  the  sun  pre- 
viously found.  Then  clamp  the  plate  and  sight  vanes 
of  the  instrument.  Turn  the  ship  by  means  of  the  rudder 
until  the  sight  vanes  are  direfcted  toward  the  sun,  and  keep 
them  in  this  position  until  the  exact  instant  of  the  local 
apparent,  time  selected.  At  that  instant  the  ship's  head 
will  correspond  with  the  correct  magnetic  direction  required; 
any  difference  shown  by  the  compass  at  that  instant  will 
be  the  deviation  for  that  heading. 

Illustration. — Let  it  be  required,  on  September  12,  1904, 
to  head  the  ship  correct  magnetic  North  at  2:20  p.  M. 
local  apparent  time.  At  the  hour  selected  the  ship  is 
estimated  to  be  near  Cape  Flattery  in  lat.  44°  30'  N  and 
long.  126°  W,  the  variation  for  that  locality  being  about 
23°  E.  Proceed  as  follows:  First  find  the  Greenwich 
apparent  time  corresponding  to  the  local  apparent  time- 
selected,  and  then   the   declination;   thus, 

L.  App.  T.,  Sept.  12  =   2^  20"'  P.  m. 
Long.  W.  in  time     =   8''  24*" 
G.  App.  T.,  Sept.  12  =  10"  44"<  p.  m. 
Sun's  Decl.  =  N  4°  14'  58"  Change  in  l^-S?" 

Corr.  for   lO.?"-        -10'  10"  X  10.7^ 

Corr.  Decl.  =  N  4°    4'  48"  609^9 

Corr.  =  10' 9.9" 


TERRESTRIAL  NAVIGATION  91 

The  azimuth  tables  are  then  entered  with  the  local  apparent 
time,  the  latitude,  and  th6  declination;  the  corresponding 
true  azimuth  is  found  to  be  N  132°  W.  The  variation 
applied  to  this  will  give  the  sun's  magnetic  azimuth,  or 
bearing;  thus, 

True  azimuth  =  N  132°  W 
Variation  =         23°  E 
Sun's  Mag.  bearing  =  N  155°  W  or  S  25°  W,  at  2:20  p.  m. 

Before  reaching  the  locality  decided  on,  set  the  north 
point  of  the  pelorus  to  correspond  with  the  ship's  head,  and 
the  sight  vanes  to  S  25°  W,  clamping  both  plate  and  vanes. 
A  few  minutes  before  2 :20  p.  m.  turn  the  ship  so  that  the 
vanes  point  directly  toward  the  sun;  keep  them  in  this 
direction  by  means  of  the  helm  until  the  watch  set  to  local 
apparent  time  (or  its  equivalent  in  mean  time)  shows 
2  :20  P.  M.  At  that  instant,  the  ship  is  heading  correct  mag- 
netic north.  Suppose  the  steering  compass  at  that  time 
shows  N  ^  W;  the  deviation  will  then  be  *  point  or  5.5°  E, 
because  the  compass  north  falls  to  the  right  of  the  magnetic 
north. 

If  it  be  required  at  any  time  to  find  the  true  course  the 
ship  is  heading,  the  sight  vanes  of  the  pelorus  are  set  and 
clamped  at  an  angle  equal  to  the  true  azimuth,  corresponding 
to  time,  declination,  and  latitude  at  observation;  at  the 
proper  time  the  sight  vanes  are  swung  in  the  direction  of  the 
sun,  when  the  lubber  line  of  the  pelorus  will  give  the  true 
course  on  which  the  ship  is  heading.  By  applying  to  this 
the  variation  of  the  locality  the  deviation  for  heading  is 
readily  found. 

TERRESTRIAL  NAVIGATION 

TERMS  RELATING  TO  NAVIGATION 
A  sphere  is  a  solid  bounded  by  a  surface  every  point  of 
which  is  at  equal  distance  from  a  fixed  common  point 
called  the  center.  A  radius  of  a  sphere  is  a  straight  line 
drawn  from  the  center  to  the  surface.  A  straight  line 
passing  through  the  center  and  terminated  at  both  ends 
by  the  surface  is  called  a  diameter  of  the  sphere. 


92  TERRESTRIAL  NAVIGATION 

A  great  circle  is  a  section  of  a  sphere  made  by  a  plane 
passing  through  its  center.  The  shortest  distance  measured 
on  the  surface  between  two  points  on  a  sphere  is  the  arc 
of  the  great  circle  joining  these  two  points. 

A  small  circle  is  a  section  of  a  sphere  made  by  a  plane 
that  does  not  pass  through  the  center. 

Hemisphere. — A  great  circle  divides  the  sphere  into 
two  equal  parts,  each  of  which  is  called  a  hemisphere. 

A  spherical  angle  is  the  angle  subtended  between  two 
great  circles. 

A  spherical  triangle  is  a  portion  of  a  sphere  bounded  by 
three  arcs  of  great  circles. 

The  axis  of  the  earth  is  the  diameter  around  which  the 
earth  daily  revolves  with  uniform  motion  from  west  to 
east;  the  revolution  being  completed  in  24  hr. 

The  poles  of  the  earth  are  the  extremities  of  its  axis, 
or  the  points  in  which  the  axis  meets  the  surface. 

The  equator  is  a  great  circle  on  the  earth's  surface  equidistant 
from  the  poles.  It  divides  the  earth  into  two  equal  parts — 
the  northern  hemisphere  and  the  southern  hemisphere.  The 
poles  of  the  earth  are  the  poles  of  the  equator,  every  point 
of  the  latter  being  90°  from  either  pole.  The  equator  of 
the  earth  is  generally  referred  to  as  the  terrestrial  or  geo- 
graphical equator. 

The  meridians  of  the  earth  are  great  circles  that  pass 
through  the  poles  of  the  earth,  and  are  therefore  perpen- 
dicular to  the  equator. 

Prime  Meridian. — The  first,  or  prime,  meridian  is  that 
fixed  meridian  by  reference  to  which  the  longitude  of  places 
on  the  earth  is  measured;  as,  for  example,  the  meridian 
of  Greenwich. 

Parallels  of  latitude  are  small  circles  whose  planes  are 
parallel  to  the  plane  of  the  equator. 

Latitude. — The  latitude  of  any  place  is  the  distance 
north  or  south  from  the  equator  measured  on  the  meridian 
that  passes  through  the  place;  it  may  be  of  any  value  from 
0°  to  90°  N  or  S. 

Longitude. — The  longitude  of  any  place  is  the  distance 
in  arc  east  or  west  measured  on  the  equator  from  the  first 


TERRESTRIAL  NAVIGATION  93 

meridian  to  the  meridian  passing  through  that  place.  Lon- 
gitude is  reckoned  from  0°  to  180°  E  or  W,  but  is  never 
considered  greater  than  180°  either  way.  Longitude  is 
also  measured  in  hours,  minutes,  and  seconds,  each  hour 
being  equal  to  15°. 

Difference  of  latitude  is  the  arc  of  a  meridian  contained 
between  the  two  latitude  parallels  passing  through  any 
two  places. 

Difference  of  longitude  is  the  portion  of  the  equator 
contained  between  the  meridians  passing  through  any 
two  places. 

Rhumb. — When  a  ship  is  kept  on  one  continuous  course, 
her  track  crosses  the  meridians  at  the  same  angle.  The 
line  representing  this  track  is  called  the  rhiimb  or  loxodromic 
curve. 

The  distance  between  two  places,  or  the  distance  run 
by  the  ship  on  any  course,  is  the  length  of  the  rhumb  joining 
the  two  places,  expressed  in  miles. 

Departure  is  the  distance  made  good  by  a  ship  due  east 
or  west,  or  the  distance  between  any  two  places  measured 
on  one  of  their  parallels;  it  is  expressed  in  miles. 

The  course  made  good  is  equivalent  to  true  course,  or  the 
angle  between  a  meridian  and  the  ship's  track  over  ground. 

The  bearing  of  an  object  or  place  is  the  angle  that  the 
direction  of  the  object  or  place  makes  with  the  meridian, 
and  is  the  same  as  the  course  toward  it. 

Plane  sailing  is  the  method  of  finding  the  ship's  position 
by  assuming  the  surface  sailed  over  to  be  a  plane.  It  is 
used  only  for  short  runs. 

Middle  latitude  of  two  plages  is  the  latitude  of  a  parallel 
midway  between  the  two  places;  or,  it  is  equal  to  half  the 
stim  of  the  two  latitudes  when  the  places  considered  are 
on  the  same  side  of  the  equator. 

Parallel  sailing  is  the  method  of  calculating  a  ship's  position 
when  the  ship  has  run  a  continuous  course  true  east  or  true  west. 

Middle-latitude  sailing  is  a  combination  of  plane  and 
parallel  sailing,  or  a  method  of  calculating  the  position  of 
a  ship  by  assuming  that  the  departure  made  by  the  ship 
is  equal  to  the  distance  along  the  middle-latitude  parallel. 


94  TERRESTRIAL  NAVIGATION 

Mercator's  sailing  is  a  method  of  calculating  the  position  of 
a   ship  by  using  meridional  parts. 

Meridional  parts  of  a  certain  latitude  give  the  length, 
expressed  in  minutes  of  the  equator,  of  the  line  on  a 
Mercator's  chart  that  represents  the  latitude. 

Meridional  difference  of  latitude  is  the  difference  between 
the  meridional  parts  for  any  two  latitudes;  or,  the  length 
of  the  line  on  a  Mercator's  chart  that  represents  the  differ- 
ence of  latitude. 

Traverse  sailing  is  the  method  of  reducing  to  a  single 
course  and  distance  the  several  courses  and  distances  run 
by  a  vessel  during  a  certain  period  of  time. 

Traverse  tables  are  a  collection,  in  tabular  form,  of  the 
lengths  of  the  sides  of  a  right  triangle  in  which  one  acute 
angle  (course)  varies  from  1°  to  89°,  and  the  hypotenuse 
(distance)  from  1  to  300  mi.;  or,  they  contain  the  true  differ- 
ence of  latitude  and  departure  corresponding  to  every 
course  from  0°  to  90°,  and  for  every  distance  from  1  to 
300  mi. 

Great-circle  sailing  is  the  various  methods  of  determining, 
graphically,  or  by  calculation,  the  compass  courses  and 
distances  to  be  run  in  order  to  follow  the  great-circle  track 
from  one  place  to  another. 

Initial  course  is  the  first  course  run  along  a  great-circle 
track. 

Final  course  is  the  last  course  run  along  a  great-circle 
track. 

Point  of  maximum  separation  is  the  point  of  a  great-circle 
track  that  is  farthest  from  the  rhumb  track.  At  this  point, 
the  courses  on  both  tracks  are  parallel  with  each  other. 

Vertex  of  a  great  circle  is  the  point  on  a  great  circle  having 
the  highest  latitude. 

Composite  sailing  is  a  combination  of  great-circle  and 
parallel  sailing. 

NAVIGATION  BY  DEAD  RECKONING 

The  cases  of  sailing  that  most  frequently  present  them- 
selves in  the  actual  navigation  of  a  vessel  may  consistently 
be  said  to  be  two  in  number,  as  follows: 


TERRESTRIAL  NAVIGATION 


95 


1.  When  the  latitude  and  longitude  of  two  places  are 
known,  to  find  the  course,  distance,  and  departure  from 
one  place  to  the  other. 

2.  When  the  place  left  and  the  course  and  distance 
run  are  known,  to  find  the  latitude  and  longitude  of  the 
place  arrived  at. 

Either  of  these  cases  may  be  worked  by  middle  latitude 
or  Mercator's  sailing,  according  to  formula  given  in  the 
accompanying  table. 


Cases 

Middle-Latitude 
Sailing 

Mercator's 
Sailing 

Both    latitudes 
and    longitudes 
given,  to  find 
course,    distance, 
and    departure. 

Dep.  =  D.     Long.  X 
cos  M.  Lat. 

tan  C  =  cos   M.   Lat. 
X  D.  Long.  ^  D. 
Lat. 

tanC  =  Dep.H-D.Lat. 

Dist.  =  D.    Lat.  X 
sec  C 

Dist.  =  Dep.  X  co- 
sec  C 

tan  C  =  D.  Long.  ^ 

M.  D.  Lat.  • 
Dist.  =  D.    Lat.  X 

secC 
Dep.  =  D.    Lat.  X 

tanC 
Dep.  =  (D.  Lat.  X 

D.    Long.)    -^    M. 

D.  Lat. 

Place    left,    course 
and  distance  known, 
to   find   difference  of 
latitude,     departure, 
and  difference  of  lon- 
gitude 

D.  Lat.  =  Dist.  X 

cosC 
Dep.  =  Dist.  X  sin  C 
D.  Long.  =  Dep.  X 

sec  M.  Lat. 
D.  Long.  =  D.  Lat.  X 

tan  C X  sec  M.  Lat. 

Dep.  =  Dist.X  sinC 
D.  Lat.  =  Dist.  X 

cos  C 
D.  Long.  =  M.  D. 

Lat.  X  tan  C 
D.  Long.  =  (Dep.X 

X  M.  D.  Lat.)  -r 

D.  Lat. 

If  the  distance  is  less  than  300  mi.,  the  middle-latitude 
method  may  be  used;  if  greater  than  300  mi.,  Mercator's 
method  should  be  employed,  except  in  cases  where  the 
course  is  large  or  very  near  east  or  west,  when  it  is  pref- 
erable to  use  the  former  method. 

The  reason  it  is  preferable  to  use  the  middle-latitude 
method  in  finding  the  difference  of  longitude  when  the 
course  is  large,  is  that  tangents  for  angles  between  80  —  90° 


96  TERRESTRIAL  NAVIGATION 

change  very  rapidly,  and  hence  when  using  the  formula 
D.  Long.  =  M.  D.  Lat.  X  tan  C,  if  there  is  an  error 
in  the  course,  the  resulting  D.  Long,  will  be  considerably 
in  error.  Therefore,  when  the  course  is  large  or  nearly  90°, 
it  is  better  to  find  the  difference  of  longitude  by  the  middle- 
latitude  formula,  D.  Long.  =  Dep.  X  sec  M.  Lat.,  in  which 
the  tangent  is  not  used. 

Example. — A  ship   in  lat.  37°  3'  N  and  long.  23°  18'  W 
is  bound  for  a  point,  the  latitude  and  longitude  of  which 
are.  respectively,  32°  38'  N  and  31°  13'  W;  required  the 
true  course  and  the  number  of  miles  to  be  covered. 
Solution  By  Middle-Latitude  Method. — 
Lat.  left  =  37°    3'  N 
Lat.  in  =  32°  38'  N 
D.  Lat.  =   4°  25'  =  265'  S 
Sumof  Lats.  =  69°  41' 

i  sum  =  34°  50'  =  M.  Lat. 
Long,  left  =  23°  18'  W 
Long.  in  =  31°  13'  W 
D.  Long.  =   7°  55'  =  475'  W 
tan  C  =  cos  M.  Lat.XD.  Long.s-D.  Lat. 
log  cos  34°  50' =  9.91425 
log  475=   2.67669 
a.  c.  log  265=   7.57675 
log  tan  C  =  10.16769 

Course  =  S55°  48' W.     Ans. 
Dist.  =  D.  Lat.  X  sec  C. 
log  265=   2.42325 
log  sec  55°  48'  =  10.2=^020 
log  Dist.=   2.67345 

Dist.  =  471.5  mi.     Ans. 
By  Traverse    Tables. — Enter   the  Tables  with  the  M.  Lat. 
34°  50'  (or  35°  nearly)  as  course  and  the  D.  Long.  475'  in 
the    distance    column,  when  the    departure    will    be    found 
in  the  latitude  column.     Thus, 

for  300  we  get  245.7 

for  175  we  get  143.4 

Whence,  for  475  we  get  389.1  mi.  as  departure 


TERRESTRIAL  NAVIGATION  97 

Having  found  the  departure,  enter  the  Tables  again 
with  132.5  (half  D.  Lat.)  and  194.5  (half  Dep.)  in  a  latitude 
and  departure  column,  respectively,  and  find  the  corre- 
sponding course  and  distance.  The  course  thus  found 
is  nearly  56°,  or  5  points  and  half  the  distance  is  235,  which, 
when  doubled,  gives  the  distance  as  470  mi.     Ans. 

Example.— X  ship  in  lat.  32°  15'  N  and  long.  67°  52'  W 
is  bound  for  a  point  in  lat.  49°  57'  N  and  long.  8°  12'  W; 
find  the  true  course  and  distance  to  be  run. 

Solution. — By  Mcrcator's  Sailing. — First  find  the  D.  Lat., 
the  M.  D.  Lat.,  and  the  D.  Long,  as  follows,  and  then 
calculate  the  course  and  distance  according  to  proper  formulas 
taken  from  the  preceding  table. 

1st  Lat.  =  32°  15'  N  M.  P.  =  2,033.9 

2d  Lat.  =  49°  57' N  M.  P.  =  3,452.2 

Lat.  =  1,418.3 


D.  Lat. 
or 

=  17°  42' 
=  1,062'  N. 

1st  Long. 

2d  Long. 

M.  D. 

=  67°  52'  W 
=   8°  12'  W 

D.  Long, 
or 

=  59°  40' 
=  3,580'  E 

tan 
log 

C  =  D.  Long 

3,580  (  +  10)  = 

log  1,418.3  = 

log  tan  C  = 

Course  = 

^M.  D.  Lat 
13.55388 
3.15168 

10.40220 

-N  68°  23'  E 

Ans. 

Dist.  =  D.  Lat.  X  sec.  C 
log  1,062=   3.02612 
log  sec  68°  23' =  10.43369 
log  Dist.=   3.45981 

Dist.  =  2,883  mi.  Ans. 
By  Traverse  Tables. — Enter  the  Tables  with  M.  D.  Lat. 
in  a  latitude  column  and  the  D.  Long,  in  a  departure  column, 
and  find  the  corresponding  course.  Then,  with  this  course 
and  the  D.  Lat.,  find  the  required  distance.  In  this  case, 
the  numbers  1,418  and  3,580  are  too  large,  and  we,  there- 
fore, divide  each  by  100  and  enter  the  Tables  with  14.1  and 


98  TERRESTRIAL  NAVIGATION 

35.8  instead  and  get  a  course  of  68°.  Then,  with  the  corre- 
sponding course  68°  and  the  D.  Lat.  worked  by  similar 
artifice,  1,062-^10  =  106.2,  the  distance  found  is  2,835. 
Now,  this  distance  does  not  agree  with  that  obtained  by 
calculation,  but  can  be  made  much  closer  by  a  simple  pro- 
portion, if  deemed  necessary.  The  correct  course  is  68°  23', 
not  68°,  and  we  therefore  must  make  an  allowance  for  the 
23';  thus, 

with  68°  as  course  and  1,062  D.  Lat.,  the  dis- 
tance is 2,835  mi. 

and  with  69°  as  course  and  1,062  D.  Lat.,  the  dis- 
tance is 2,963  mi. 

The  difference,  therefore,  for  60'  of  the  course  is        128  mi. 

23  X  128 
Whence,  for  23'  it  must  be  — ^77 —  =  49  mi.     This,  when 
oO 

added  to  the  distance  corresponding  to  the  lesser  course,  will 

produce  a  more  correct  value  of  the  required  distance,  or 

49  +  2,835  =  2,884  mi.,  which  very  nearly  agrees  with  that 

derived  by  computation.     Ans. 

Example. — From  a  place  in  lat.  52°  6'  N  and  long.  38° 
27'  W,  a  vessel  runs  N  56°  W,  229  mi.;  find  her  latitude 
and  longitude  in. 

Solution. — By  the  Middle-Latitude  Method. — 

D.  Lat.  =  Dist.  X  cos  C  Lat.  left  =  52°    6'  N 

log  229=   2.35984  D.  Lat.=   2°    8.1' N 

log  cos  56°=   9.74756  ,    ^    .        -.„,.,,  .,       . 

Lat.  in  =  54°  14.1'  N.     Ans. 

log  D.  Lat.=   2.10740         Sum  of  Lats.  =  106°  20.1' 

D.  Lat.  =  128.1' N  i  sum=   53°  10'  =  M.  Lat. 

D.  Long.  =  D.  Lat.  X  tan  CXsec  M.  Lat. 

log  128.1=   2.10740 

log  tan  56°  =  10.17101 

log  sec  53°  10' =  10.22222 

log  D.  Long.  =    2.50063 

D.  Long.  =  316.7'  W 

Long,  left  =  38°  27'  W 
D.  Long.  =  316.7'=   5°  16.7' W 

Long,  in  =  43°  43.7'  W.     Ans. 


TERRESTRIAL  NAVIGATION  99 

By  Traverse  Tables. — Enter  Tables  with  course  56°  and 
distance  229  and  find  the  corresponding  D.  Lat.  128.1  and 
Dep.  189.8  in  their  respective  columns.  Then,  with  the 
M.  Lat.  as  course  and  the  Dep.  just  found,  enter  the  Tables 
again  with  Dep.  in  a  latitude  column  when  the  required 
D.  Long,  is  found  in  the  distance  column.     Thus, 

for  144.4  we  get  240'  D.  Long. 

for    45.4  we  get    76'  D.  Long. 

Whence,        for  189.8  we  get  316'  D.  Long. 
This  applied  to  the  longitude  left  will  give  the  longitude 
in  as  43°  43'  W.     Ans. 

Example. — From  a  point  situated  in  lat.  49°  52'  S  and 
long.  27°  15'  W,  a  ship  steams  513.5  mi.,  steering  a  true 
course  N  26°  36'  E;  find  the  latitude  and  longitude  in. 
Solution.- — By  Mercator's  Sailing. — 

D.  Lat.  =  Dist.Xcos  C 
log  513.5  =  2.71054 
log  cos  26°  36' =  9.95141 


log  D.  Lat.  =  2.66195 

D.  Lat.  =  459.1'  N 

Lat.  left  =  49°  52'  S 

D.  Lat.=   7°39' N  M.  P. =3444.5 

T    *   •       .00  iQ,  c                                                 M.  P.  =  2783.8 
Lat.  m  =  42°  13'  S  


M.  D.  Lat.=   660.7 
D.  Long.  =  M.  D.  Lat.  X  tan  C 

log  660.7  =2.82000  Long,  left  =  27°  15'  W 

log  tan  26°  36' =  9.69963  D.  Long.=    5°  31'  E 

log  D.  Long.  =  2.51963  Long,  in  =  21°  44'  W.  Ans. 

D.  Long.  =  330.8'  E 

By  Traverse  Tables.— Entering  the  Tables  with  N  26° 
36'  E  and  the  distance  513.5,  the  corresponding  D.  Lat. 
is  found  to  be  459.4'.  This  value  is  obtained  by  taking  the 
mean  of  the  D.  Lat.  for  26°  and  27°,  respectively,  the  corre- 
sponding course  being  26^°,  nearly.  To  find  the  D.  Long., 
the  Tables  are  entered  again  in  a  similar  manner  with 
course  and  the  M.  D.  Lat.,  660.7,  in  a  latitude  column  when 
the  required  D.  Long,  is  found  in  the  departure  column.  Ans. 


100  TERRESTRIAL  NAVIGATION 

THE  DAY'S  WORK 

The  operation  of  calculating  at  each  noon  the  course  and 
distance  made  good  during  the  past  24  hr.  is  commonly 
known  as  the  day's  work.  Each  compass  course  run  dur- 
ing the  day  is  converted  to  true  and,  together  with  its  dis- 
tance, entered  in  a  traverse,  whence  the  course  and  distance 
made  good  and  the  latitude  and  longitude  in  are  found  from 
the  total  D.  Lat.  and  Dep..  either  by  calculation  or  by 
inspection  of  the  Traverse  Tables,  as  shown  in  the  following 
example.  Strictly  speaking,  the  day's  work  includes  the 
finding  of  the  ship's  position  both  by  dead  reckoning  and 
astronomical  observations.  In  the  example  that  follows 
only  the  former  method  is  considered. 

The  official  log  book  of  a  ship  should  contain  a  carefully 
prepared  record  of  the  day's  work,  and,  in  fact,  all  important 
happenings  that  may  occur  on  board  ship.  In  it  should  be 
entered  courses  and  distances  run,  with  amount  of  leeway, 
variation,  and  deviation  applicable  to  each.  This  is  usually 
done  at  the  end  of  each  watch  by  the  officer  in  charge  of  the 
deck,  who  inserts  them  in  a  scrap  log;  from  the  scrap  log  they 
are  subsequently  transferred  to  the  official  log  book. 

Example. — On  June  16,  1904,  at  noon,  a  point  in  lat. 
51°  53'  N  and  long.  55°  22'  Wbore  NNW  by  compass,  the 
estimated  distance  being  48  mi.  When  bearing  was  taken 
the  ship  headed  S  E  by  S,  the  deviation  for  that  point  being 
recorded  in  the  appended  log  account.  From  the  place 
where  bearing  was  taken  the  following  compass  courses  and 
distances  were  run;  find  course  and  distance  made  good 
and  the  latitude  and  longitude  of  the  ship  at  noon  June  17, 
assuming  a  current  setting  correct  magnetic  east,  li  mi. 
per  hr.,  to  have  uniformly  affected  the  ship  during  the 
entire  run  from  noon  to  noon. 


TERRESTRIAL  NAVIGATION 
LoG-BooK  Account 


101 


June  16 

e 

i2 

in 

5 

§ 

0 

c 

C 

Courses 

Wind 

A 

Dev. 

Remarks 

K 

W 

^ 

1 

12 

0 

South 

ESE 

i 

0 

p.  M. 

2 

11 

5 

3 

13 

0 

4 

13 

5 

5 

13 

5 

SSE 

East 

0 

11"  W 

6     13 

5 

7  !  12 

5 

Var.36°W 

8 

12 

5 

9 

12 

5 

SE  by  S 

Eby  N 

i 

18°  W 

10 

12 

5 

11 

13 

0 

12 

12 

0 

Midnight 

June  17 

1 

12 

0 

ESE  JE 

NE 

1 

27°  W 

A.  M. 

2 

12 

0 

3 

12 

0 

4 

12 

0 

5 

12 

0 

E  i  N 

NNE 

i 

29°  W 

6 

11 

5 

7 

12 

0 

Var.36°  W 

8 

10 

5 

9 

10 

5 

S  by  E  J  E 

East 

i 

8°W 

10 

10 

0 

11 

11 

5 

12 

12 

0 

Noon 

Solution. — Correct  each  compass  course  for  variation, 
deviation,  and  leeway;  take  the  sum  of  distances  run  on 
each  course.  Correct  current  for  variation  and  consider  it 
as  a  separate  course  run.  Reverse  bearing,  apply  the 
necessary  corrections,  and  enter  it  with  the  estimated  dis- 
tance in  the  Traverse  as  the  first  course  and  distance  run. 
Thus, 


102  TERRESTRIAL  NAVIGATION 

1st  Comp.  C.  =  South  2d  Comp.  C.  =  S  22°  30'  E 

Leeway  =       2°  49'  Dev.=     11°    0' W 


S    2°  49'  W  S  33°  30'  E 

Var.  =     36°    0'  W  Var.  =     36°    0'  W 


True  C  =  S33°  11' E  True  C  =  S  69°  30'  E 

Dist.  50  mi.  Dist.  52  mi. 

8d  Comp.  C.  =  S33°45' E  4th  Comp.  C.= 
Leeway  =       2°  49'  Leeway  = 


Dev.  =     18°    0'  W  Dev. 


S30° 
18° 

56' 
0' 

E 
W 

S48° 
36° 

56' 
0' 

E 
W 

S 

70° 

19' 

E 

11° 

15' 

S 

59° 

4' 

E 

27° 

0' 

W 

s 

86° 

4' 

E 

36° 

0' 

W 

Var.  =     36°    0'  W  Var. 

True  C.  =  S84°56'  E  True  C.  =  S  122°    4'  E 

Dist.  50  mi.  or  =  N57°56'E 

Dist.  48  mi. 
6th  Comp.  C.  =  N  84°  22'  E  6th  Comp.  C.  =  S  14°    4'  E 

Leeway  =        5°  38  Leeway  =       5°  38' 


Dev.  =      29°    0'  W  Dev. 


N  90° 
=      29° 

0'  E 
0'  W 

N61° 
'      36° 

O'E 
0' W 

S    8° 

26' 

E 

=       8° 

0' 

W 

S  16° 

26' 

E 

=     36° 

0' 

W 

Var.  =      36°    0'  W  Var. 

True  C.  =  N  25°    C  E  True  C.  =  S  52°  26'  E 

Dist.  46  mi.  Dist.  44  mi. 

Bearing  rev'd.  =  S  22°  30'  E     Current  (mag.)  =  N  90°  E 
Dev.  for  SE  by  S=     18°    0' W  Var.=      36°  W 

S  40°  30' ¥  True  set  =  N  54°  E 

Var.  =     36°    0'  W  Rate  or  distance 

True  rev'd.  bear.    =  S  76°  30'  E  for24h  =  36mi. 

Dist.  48  mi. 
Enter  the  true  courses  thus  found  in  a  Traverse  arranged 
in  the  form  shown,  and  find  from  Traverse  Tables  the  D.  Lat. 
and  Dcp.  corresponding  to  each  course  and  distance.  The 
total  D.  Lat.  and  Dep.  made  by  the  ship  is  found,  respect- 
ively, by  taking  the  algebraic  sum  of  northerly  and  southerly 
differences  of  latitudes  and  easterly  and  westerly  departures. 


TERRES TRIAL  NA  VIGA TION 

103 

TRAVERSE 

D.  Lat. 

Dep. 

True 

.1 

Courses 

N 

S 

E 

W 

S77°  E 

48 

10.8 

46.8 

S33°E 

50 

41.9 

27.2 

S  70°  E 

52 

17.8 

48.9 

S85°E 

50 

4.4 

49.8 

N  58°  E 

48 

25.4 

40.7 

N  25°  E 

46 

41.7 

19.4 

S52°E 

44 

27.1 

34.7 

N  54°  E 

36 

21.2 

29.1 

88.3      102.0     296.6    E  =  Dep. 

D.  Lat.= 

88.3 

5 

13.7' i 

Lat. 

left  =  51°  53'  N 

Lat.  in  =  51°39.3'  N. 
M.  Lat.  =  51°  46' 


Ans. 


For  Course 

tan  C"  =  Dep.-^D.  Lat 

log  296.6=   2.47217 

log  13.7=    1.13672 

log  tan  C  =  11.33545 

Course  =  S  87°  21' E.     Ans. 


For  Distance 

Dist.  =  D.  Lat.  X  sec  C 

log  13.7  =  1.13672 

log  sec  C  =  1.33503 

log  Dist.  =  2.47175 

Dist.  =  296.3  mi.    Ans. 


For  Diff.  Longitude  For  Longitude  In 

D.  Long.  =  Dep.  X  sec  M.  Lat.     Long,  left  =  55°  22'  W 
log  296.6  =  2.47217  D.  Long.=   7°  59.3'  E 

log  sec  M.  Lat.  =    .20840  Long,  in  =  47°  22.7' W.  Ans. 

log  D.  Long.  =  2.68057 
D.  Long.  =  479.3'  E 

The  required  data  are  found  also  by  inspection  of  Traverse 
Tables  in  the  usual  manner.  Thus,  the  nearest  whole 
degree  course  corresponding  to  the  D.  Lat.  13.7  and  Dep. 
296.6  is  S  87°  E,  the  distance  by  tables  being  297  mi.; 
with  M.  Lat.  52°  as  course  and  29.6  in  a  latitude  column. 


104 


TERRESTRIAL  NAVIGATION 


the  corresponding  number  found  in  distance  column  is  48, 
which  multiplied  by  10  gives  the  D.  Long,  as  480'. 


LENGTHS,    IN    NAUTICAL    MILES,    OF    A    DEGREE    OF 

LONGITUDE    FOR  EACH  DEGREE  OF  LATITUDE 

FROM  0°  TO  90° 


Lat. 

Lat. 

Lat. 

De- 

Miles 

De- 

Miles 

De- 

Miles 

grees 

grees 

grees 

1 

59.99 

31 

51.43 

61 

29.09 

2 

59.96 

32 

50.88 

62 

28.17 

3 

59.92 

33 

50.32 

63 

27.74 

4 

59.85 

34 

49.74 

64 

26.30 

5 

59.77 

35 

49.15 

65 

25.36 

6 

59.67 

36 

48.54 

66 

24.40 

7 

59.55 

37 

47.92 

67 

23.44 

8 

59.42 

38 

47.28 

68 

22.48 

9 

59.26 

39 

46.63 

69 

21.50 

10 

59.09 

40 

45.96 

70 

20.52 

11 

58.89 

41 

45.28 

71 

19.53 

12 

58.69 

42 

44.59 

72 

18.54 

13 

58.46 

43 

43.88 

73 

17.54 

14 

58.22 

44 

43.16 

74 

16.54 

15 

57.95 

45 

42.43 

75 

15.53 

16 

57.67 

46 

41.68 

76 

14.52 

17 

57.38 

47 

40.92 

77 

13.50 

18 

57.06 

48 

40.15 

78 

12.48 

19 

56.73 

49 

39.36 

79 

11.45 

20 

56.38 

50 

38.57 

80 

10.42 

21 

56.01 

51 

37.76 

81 

9.38 

22 

55.63 

52 

36.94 

82 

8.35 

23 

55.23 

53 

36.11 

83 

7.31 

24 

54.81 

54 

35.27 

84 

6.27 

25 

54.38 

55 

34.41 

85 

5.23 

26 

53.93 

56 

33.45 

86 

4.18 

27 

53.46 

57 

32.68 

87 

3.14 

28 

52.97 

58 

31.79 

88 

2.00 

29 

52.48 

59 

30.09 

89 

1.05 

30 

51.96 

60 

30.00 

90 

.00 

TERRESTRIAL  NAVIGATIOX  105 

CONSTRUCTING  A  MERCATORIAL  CHART 

First,  determine  the  limits  of  the  proposed  chart — in  other 
words,  the  number  of  degrees  and  minutes  it  is  to  contain, 
both  of  latitude  and  of  longitude.  Then  draw  a  straight 
line  near  the  lower  margin  of  the  paper,  if  the  chart  is  to 
represent  north  latitude;  near  the  upper  margin,  if  it  is  to 
represent  south  latitude;  or  at  a  suitable  position  in 
the  center,  if  both  north  and  south  latitudes  are  to  be 
represented.  Divide  this  base  line  into  as  many  equal 
parts  as  the  number  of  degrees  of  longitude  required;  for 
instance,  if  the  chart  is  to  contain  15°  of  longitude,  divide 
the  line  into  15  equal  parts;  if  it  is  to  contain  4°  of  longi- 
tude, divide  it  into  4  equal  parts.  At  each  extremity  of 
the  base  line,  erect  lines  perpendicular  to  it.  Take  from 
the  Tables  of  Meridional  Parts  CI.  C.  S.  Nautical  Tables,  or 
Bowditch)  the  meridional  parts  for  each  degree  of  latitude, 
for  the  limits  between  which  the  chart  is  to  be  drawn,  and 
take  the  difference  between  each  successive  pair,  thus 
obtaining  the  meridional  differences  of  latitude.  Reduce 
these  meridional  differences  to  degrees  by  dividing  them 
by  60;  the  result  will  be  the  lengths,  measured  on  the  longi- 
tude scale,  between  the  chosen  degrees  of  latitude.  Lay 
off  these  lengths  successively  on  the  perpendicular  lines, 
and  through  the  points  thus  obtained  draw  straight  lines 
parallel  to  the  base  line,  to  represent  latitude  parallels. 
At  convenient  intervals,  or  through  each  division  on  the 
base  line,  draw  lines  parallel  to  the  perpendiculars  to  rep- 
resent meridians. 

The  accuracy  of  the  frame  of  the  chart  thus  completed 
should  be  tested  by  measuring  the  two  diagonals  of  the 
rectangle  formed;  if  they  are  of  the  same  length,  the  frame 
is  perfect.  Then  graduate  the  scale  into  suitable  divisions 
of  5'  or  10'  each,  or  if  deemed  necessary  divide  each  degree 
into  60  divisions,  which  will  then  represent  minutes.  The 
principal  points  in  the  chart  are  now  laid  down  according 
to  their  respective  latitudes  and  longitudes,  and  whatever 
formations  and  contours  of  water  or  land  are  required, 
together  with  other  useful  items,  are  drawn  in  freehand. 
Compass    diagrams    may    also    be    inserted    at    convenient 


106  TERRESTRIAL  NAVIGATION 

places,  remembering  that  the  direction  of  the  meridians 
indicates  true  north  and  south. 

Example. — Construct  a  Mercator's  chart  extending  from 
lat.  40°  to  43°  N  and  from  long.  105°  to  108°  E,  on  a  scale 
of  2  in.  to  a  degree  of  longitude.  On  this  chart,  plot  the 
following  positions:  A  lat.  41°  10'  N,  long.  105°  36'  E; 
B  lat.  42°  15'  N,  long.  107°  30'  E;  and  C  lat.  42°  40'  N, 
long.  106°  12'  E.  Find  the  true  course  from  A  to  B,  then 
from  B  to  C. 

Solution. — Referring  to  the  chart,  draw  a  line  a  6  at 
the  bottom  margin  of  the  paper  to.  represent  the  40th 
parallel.  On  this  base  line,  lay  off  three  lengths  of  .2  in. 
each  and  divide  each  length  into  60  equal  parts,  repre- 
senting minutes  or  nautical  miles.  This  is  conveniently 
done  by  the  method  shown  in  the  lower  right-hand  corner 
of  the  chart,  which  consists  in  drawing  a  pencil  line  b  c  at 
an  angle  of  about  45°  from  the  extremity  of  a  degree  and 
dividing  it  into  a  desired  number  of  equal  divisions  directly 
from  the  rule  used;  the  last  division  of  this  line  is  then  con- 
nected with  the  other  extremity  d  of  the  degree,  and  lines 
parallel  to  this  line  are  drawn  from  each  division:  the  lines 
thus  drawn  will  divide  the  degree  into  the  desired  number 
of  equal  parts,  as  shown.  Proceed  similarly  in  graduating 
the  other  degrees.  Next,  consult  the  Table  of  Meridional 
Parts  and  take  out  the  values  corresponding  to  each  degree 
of  latitude  and  obtain  the  meridional  differences  of  latitude 
as  indicated  below. 

Lat.  M.  P.  M.  D.  Lat. 

40° 2,607. 9| 78.6-J-60  =  l°  18.6' 

^^° 2.686. 5  1 79.8^60  =  1°  19.8' 

42° 2,766.3{  1-60-1°  21   1' 

43° 2,847.4) ^^'^  '^""^    ^^'^ 

This  being  complied  with,  take,  with  a  pair  of  dividers, 
1"  18.6'  from  the  longitude  scale  and  lay  it  off  on  each  per^ 
pendicular  from  the  base  line;  and  through  the  points  thus 
obtained,  draw  the  parallel  of  41°.  In  like  manner,  from 
the  parallel  41°.  lay  off  the  next  length  1°  19.8'  taken  from 
the  longitude  scale,  and  draw  the  parallel  of  42°.     Proceed 


TERRES TRIAL  NA  VIGA  TION 


107 


similarly    and    get    the    parallel    of    43°.     Divide    this    last 
parallel  into  degrees  and  minutes  the  same  as  the  parallel 


iiiiiiiiiiiiiiiiiiiiiiiiiin!iniiiiii|iiiiiiiii 


|i::iiiiiHiiilliiiHlllllllii[lllliilll[lllliliii 


107°  JO'  199' 


*SC 


a 


4\.  \ 


30' 


AimsssAma^mdss 


I'lllllllllllllllllllllllllllllllllllllllllllIN 


txlx. 


Ad 


fr 


2  /nchea  'V  Unf/tu(A. 


of  40",  at  the  bottom  of  the  chart,  and  draw  the  meridians  of 
106°  and  107°  east  longitude.    The  frame  of  the  chart  is  then 


108  TERRESTRIAL  NAVIGATION 

completed  and  the  positions  A,  B,  and  C  may  now  be  plotted 
in  the  usual  manner. 

Joining  A  and  B  with  a  straight  line,  we  find  the  course 
between  the  two  points  to  be  N  53°  E.  In  like  manner,  we 
find  the  course  from  5  to  C  to  be  N  66*°  W,  nearly.     Ans. 

It  is  very  useful  to  a  navigator,  in  case  charts  are  lost  or 
destroyed,  to  be  able  to  construct  a  substitute  for  temporary 
use. 

In  connection  with  the  use  of  charts,  especially  old  charts, 
care  should  be  taken  that  all  changes  in  the  position  or 
character  of  lights,  the  establishment  of  new  or  discontin- 
uation of  existing  lights,  buoys,  landmarks,  etc.,  are  properly 
noted  on  the  chart  before  it  is  used,  also  the  exact  location 
of  sunken  wrecks  and  other  obstructions  as  given  in  Notice 
to  Mariners.  This  work  of  correcting  charts  is,  as  a  rule, 
performed  free  of  cost  by  officers  in  charge  of  Branch  Hydro- 
graphic  Offices  located  in  the  principal  ports  along  the 
seaboard. 

PLOTTING  A  GREAT-CIRCLE  TRACK 

Let  the  appended  diagram  represent  a  gnomonic,  or 
great-circle  chart,  the  straight  line  A  B  being  the  great- 
circle  track  between  the  two  places  A  and  B.  In  order  to 
transfer  this  track  to  a  Mercator's  chart,  select  a  few  points 
along  the  line  and  find,  by  inspection,  the  latitude  and 
longitude  of  each.  Plot  these  points  carefully  on  the 
Mercatorial  chart  and  draw  a  uniform  curve  passing  through 
all  points  thus  established.  This  curve  will  be  the  great- 
circle  track  and  the  courses  and  distance  to  be  run,  in  order 
to  follow  this  track,  may  be  conveniently  found  as  follows: 
Get  the  difference  between  the  initial  course  and  the  course 
at  the  point  of  maximum  separation  (equal  to  the  rhumb 
course)  and  find  how  many  quarter  points  are  contained  in 
it.  Divide  the  distance  between  the  first  place  and  the 
point  of  maximum  separation  by  this  number  of  quarter 
points;  the  result  will  be  the  number  of  miles  to  be  sailed 
on  each  quarter-point  course. 

For  instance,  assume  the  initial  course  to  be  N  W,  the 
course  at  the  point  of  maximum  separation  W  N  W,  and 


TERRESTRIAL  NA  VIGA TION 


109 


the  distance  between  these  points  800  mi.  Now,  the  difTer- 
ence  between  N  W  and  W  N  W  is  2  points,  or  8  quarter 
points;  hence,  dividing  800  mi.  by  8  will  give  100  mi.  for 
each  quarter-point  course.  In  other  words,  the  course  will 
have  to  be  changed  one-quarter  of  a  point  to  the  west  for 
every  100  mi.  run. 

Proceed,  similarly,  to  find  the  course  and  distance  front 
the  point  of  maximum  separation  to  the  point  of  destination.- 
It  is  evident  that  the  difiference  between  the  courses  cari 
be  divided  into  still  smaller  divisions  if  required;  for  instance, 
in  the  case  just  mentioned,  it  may  be  divided  into  eighths  of 
a  point ;  the  course  will  then 
have  to  be  changed  one- 
eighth  of  a  point  for  each 
50  mi.  run.  For  ordinary 
practice,  however,  quarter 
points  will  suffice. 

The  courses  thus  found 
are  true  and  must  be  cor- 
rected for  variation,  devia- 
tion, and  leeway,  if  any. 

On  great-circle  charts 
published  by  the  United 
States  Hydrographic  Office 
will  ibe  found  a  Great-Circle 
Course  Diagram,  by  which 
courses  and  distances  along 

the  track  are  conveniently  found  by  inspection.  Directions 
how  to  use  this  diagram  are  printed  on  the  chart  under  the 
head  of  Explanation. 


A       I  \  \ 


USEFUL  METHODS  IN  COAST  NAVIGATION 

Cross-Bearings. — When  the  bearings  of  two  selected 
objects  are  corrected  for  deviation,  due  to  the  direction  of 
the  ship's  head  at  the  time  of  observing  them,  place  the 
parallel  ruler  on  the  nearest  magnetic  compass  rose  on  the 
chart  so  that  the  edge  passes  through  the  center  and  the 
requisite  degree  or  point  on  the  circumference.  Then  move 
the  ruler,  step  by  step,  until  the  edge  passes  through  the 


110 


TERRESTRIAL  NA  \ 'IGA  TION 


object  when  a  light  pencil  line  drawn  along  the  edge  will 
represent  one  of  the  bearings.  The  ship  will  then  be  some- 
where on  the  line.  Proceed  similarly  with  the  other  bearing. 
Now,  the  ship  will  be  somewhere  on  this  line  also,  and  since 
the  only  common  point  of  two  lines  intersecting  each  other 
is  at  their  point  of  intersection,  the  position  of  the  ship  on 
the  chart  must  necessarily  be  at  the  point  where  the  two 
bearings  intersect. 

It  is  evident  that  the  objects  selected  for  cross-bearings 
should  be  so  situated  that  the 
lines  of  bearing  do  not  inter- 
sect at  a  very  acute  angle,  since 
the  point  of  intersection  in  such 
cases  is  somewhat  doubtful.  To 
obtain  accurate  results,  the 
angle  between  the  bearings 
should  be  as  near  as  possible  to 
90°,  or  8  points. 

Bow-Bearings. — A  compass 
bearing  is  taken  of  a  light  or 
other  prominent  known  object 
when  it  is  2,  3,  or  4  points  off 
the  bow,  and  the  time  and  log 
noted.  When  the  bearing  has 
doubled,  the  log  and  time  are 
again  noted.  (If  a  patent  log  is 
used,  it  is  not  necessary  to  note 
the  time,  but  simply  the  indi- 
cator of  the  log  at  both  bear- 
ings.) The  distance  of  the  ship 
from  the  object  is  then  equal  to  the  distance  run  in  the 
interval  between  the  first  and  second  bearing,  or,  the  differ- 
ence of  readings  of  the  patent  log  at  the  two  bearings. 

By  using  this  method  when  the  object  bears  2  or  3  points 
off  the  bow,  the  distance  of  vessel  from  A  is  known  before 
the  object  is  abeam,  as  shown  in  the  figure. 

Illustration. — Referring  to  the  figure,  suppose  that  the 
reading  of  the  patent  log  when  at  B  is  69.6  mi.,  and  when  at 
D,  or  when  bearing  is  doubled,  it  is  74.2  mi.     The  distance 


Fig.  1 


TERRESTRIAL  NAVIGATION  111 

of  ship  from  A  is  then  74.2  —  69.6  =  4.6  mi.  In  other  words, 
B  D  =  D  A;  also,  incase  C  and  E  are  considered,  C  E  =  E  A. 
This  method  is  frequently  used  when  the  ship  is  at  D,  or 
when  object  bears  4  points  off  the  bow,  and  is  then  known 
as  4-point  bearing.  Doubling  this  angle,  the  ship  is  exactly 
abeam  of  object. 

Bearings  of  Same  Object  and  Distance  Run. — A  compass 
bearing  is  taken  of  some  known  object  at  any  instant  and 
the  number  of  points,  or  degrees,  contained  between  its 
direction  and  the  ship's  head,  or  course,  are  noted.  A 
straight  continuous  course  is  then  kept  until  the  bearing  of 
the  object  has  altered  at  least  3  points,  when  another  bearing 
is  taken  and  the  number  of  points  between  it  and  the  ship's 
head  are  again  noted. 

These  angles,  if  expressed  in  points,  are  then  entered  in 
the  table  found  on  page  112,  or,  if  expressed  in  degrees,  in 
the  table  on  the  following  page,  and  the  distance  is  found  as 
follows:  "With  the  first  number  of  points,  or  degrees,  at 
the  top  and  the  second  angle  at  the  side  column,  find  the 
corresponding  number;  multiply  this  by  the  number  of 
miles  run  in  the  interval  between  bearings.  The  product 
is  the  distance,  in  miles,  at  the  time  the  second  bearing 
was  taken. 

Example. — A  certain  lighthouse  bore  N  N  W;  2  hr.  later, 
after  the  ship  had  run  true  west  12  mi.,  the  bearing  of  the 
same  light  was  N  E  by  N;  required,  the  distance  of  the  ship 
from  the  light  at  the  second  bearing. 

Solution. — The  number  of  points  included  between  the 
first  bearing  and  the  ship's  head  is  6;  between  the  second 
bearing  and  the  ship's  head  there  are  11  points.  Entering 
the  proper  Table  with  6  points  at  the  top  and  with  1 1  points 
in  the  side  column,  we  find,  below  the  former  and  opposite 
the  latter,  the  number  1.11;  multiplying  this  by  12,  the 
number  of  miles  run  in  the  interval  between  bearings, 
the  product,  1.11X12  =  13.3  mi.,  which  will  be  the  distance 
of  the  ship  from  the  light  at  the  time  of  taking  the  second 
bearing.     Ans. 


112 


TERRESTRIAL  NAVIGATION 


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TERRESTRIAL  NAVIGATION 


113 


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114 


TERRESTRIAL  XAVIGATION 


DISTANCES  OF  OBJECTS  AT  SEA,  IN  NAUTICAL  MILES 

The  maximum  distance  at  which  an  object  is  visible  at 
sea  according  to  its  elevation  and  that  of  the  observer, 
the  weather  being  clear  and  the  refraction  normal,  is  shown 
by  the  following  table: 


Height 

Distance 

Height 

Distance 

Feet 

Nautical  Miles 

Feet 

Nautical  Miles 

5 

2.56 

110 

12.07 

10 

3.63 

120 

12.60 

15 

4.44 

130 

13.12 

20 

5.15 

140 

13.62 

25 

5.75 

150 

14.08 

30 

6.30 

200 

16.26 

35 

6.81 

250 

18.18 

40 

7.27 

300 

19.92 

45 

7.71 

350 

21.51 

50 

8.13 

400 

23.00 

55 

8.53 

450 

24.39 

60 

8.91 

500 

25.71 

65 

9.27 

550 

26.97 

70 

9.62 

600 

28.17 

75 

9.96 

650 

29.32 

80 

10.28 

700 

30.43 

85 

10.60 

800 

32.53 

90 

10.91 

900 

34.50 

95 

11.21 

1,000 

36.36 

100 

11.50 

The  distances  of  visibility  given  in  the  above  table  are 
those  from  which  an  object  may  be  seen  by  an  observer 
whose  eye  is  at  the  sea  level;  in  practice,  therefore,  it  is 
necessary  to  add  to  these  a  distance  of  visibility  correspond- 
ing to  the  height  of  the  observer's  eye  above  sea  level. 

Example. — A  light  90  ft.  high  is  seen  just  at  the  horizon; 
height  of  observer  is  15  ft.  What,  under  ordinary  condi- 
tions of  the  atmosphere,  is  its  distance  from  the  observer? 

Solution. — Distance     corresponding 

to  90  ft.  is 10.91 

Add  distance  corresponding  to  height 

of  observer's  eye  above  sea  level, 

15  ft 4.44 

Distance  of  light  is 15.35  naut.  mi.     Ans. 


TERRESTRIAL  XAVIGATION  115 

Example. — A  vessel  is  running  for  a  certain  port.  At  the 
time  the  lighthouse  at  the  entrance  of  the  harbor  is  expected 
to  become  visible,  a  man  is  sent  aloft;  his  height  above 
the  water-line  is  60  ft.  After  a  while  he  discovers  the  light, 
the  height  of  which  is  75  ft. ;  what  is  the  distance  of  the  ship 
from  the  light,  in  nautical  miles? 

Solution. — Entering  table,  we  find  that 
distance  corresponding  to  60  ft.  is    8.91 
distance  corresponding  to  75  ft.  is    9.96 

Hence,  distance  from  light  is  18.87  naut.  mi.     Ans. 

Distances  corresponding  to  heights  not  included  in  the 
above  table  may  be  found  by  the  form-ula, 

in  which  H  =  elevation,  or  height,  in  feet,  of  the  object  above 
sea  level; 
£?  =  corresponding  distance  of  visibility,  in  nautical 
miles. 

The  formula  is  based  on  the  mean  curvature  of  the  earth 
and  is  corrected  for  ordinary- atmospheric  refraction.  The 
distance  of  visibility  of  a  light  may  be  augmented  by  abnor- 
mal atmospheric  refraction,  which  usually  increases  with 
the  height  of  the  barometer  and  a  falling  temperature. 

Distance  by  the  Velocity  of  Sound, — A  convenient  method, 
whenever  available,  is  to  determine  the  distance  by  noting 
the  number  of  seconds  elapsed  between  seeing  the  flash  and 
hearing  the  report  of  a  gun  fired.  The  velocity  of  sound  is 
1  naut.  mi.  in  5.6  sec.  or  .18'  (  =  1,092  ft.)  in  1  sec.  Hence, 
the  following  rule: 

Rule. — Divide  the  number  of  seconds  elapsed  by  5.6,  or, 
multiply  them  by  .18;  the  result  is  the  required  distance  expressed 
in  miles. 

Thus,  if  the  number  of  seconds  counted  in  the  interval  of 

time  between  the  flash  and  report  of  a  gun  is  14,  the  required 

14 
distance  is  --^  =  2.5;  or,  =14X. 18  =  2.52  mi. 

O.D 

Danger  Angles. — The  danger  angle,  which  may  be  either 
vertical  or  horizontal,  is  the  name  given  to  a  method  that 
is  used  when  coasting  to  avoid  hidden  dangers,  such  as  rocks. 


116 


TERRESTRIAL  NAVIGATION 


shoals,  sunken  derelicts,  and  other  obstructions  situated 
immediately  at  or  below  the  water  level.  By  its  use,  any 
such  dangerous  obstacle  may  be  passed  or  rounded  at  any 
desired  distance. 

The  vertical  danger  angle  is  based  on  the  principle  that 
the  distance  to  an  object  will  remain  the  same  as  long  as 

the  angle  subtended 
by  the  height  of  the 
object  remains  the 
same.  Tables  con- 
taining angles  corre- 
sponding to  different 
heights  and  distances 
expressed  in  miles 
and  fractions  of  a 
mile  have  accord- 
ingly been  prepared 
for  the  use  of  navi- 
gators. Thus,  if  an 
object  is  190  ft.  high 
and  it  is  required  to 
round  it  at  a  distance 
of,  for  example,  2  mi., 
the  angle  that  the  ob- 
ject should  subtend  Is 
53.7';  the  sextant  is 
then  set  and  clamped 
at  that  angle  and 
the  vessel's  course 
altered  so  that  the 
angle  will  remain  the 
Fig.  2  same.      If  the  angle 

referred  to  becomes  larger,  the  ship  is  inside  the  2-mi.  limit; 
if  smaller  it  is  outside,  or  the  distance  of  the  ship  from  the 
object  is  greater  than  2  mi. 

The  horizontal  danger  angle  is  an  application  of  the 
geometrical  properties  of  the  circle,  namely,  that  angles 
inscribed  in  the  same  segment  are  equal.  The  following 
example  will  serve  to  explain  this  method:     Suppose  that 


TERRESTRIAL  NAVIGATION  117 

when  steaming  along  a  coast  it  is  necessary  to  avoid  some 
hidden  rocks  R,  Fig.  2,  by  passing  ^  mi.  outside  of  them. 
On  the  shore,  there  are  two  known  objects  in  sight,  a  light- 
house L  and  a  church  C,  both  being  marked  on  the  chart. 
Then,  to  find  the  danger  angle  corresponding  to  a  distance 
of  \  mi.  from  the  rocks,  proceed  as  follows:  With  the  outer- 
most rock  as  a  center  and  a  radius  equal  to  ^  mi.,  describe 
a  circle  on  the  chart.  Then,  through  the  most  seaward 
point  a  of  this  circle  and  the  points  C  and  L,  describe  another 
circle;  connect  a  with  C  and  L;  measure,  with  a  protractor, 
the  angle  C  a  L  formed  by  the  lines  a  C  and  a  L.  Assume 
it  to  be  52°,  as  in  the  figure.  This  is  the  required  horizontal 
danger  angle.  Now,  set  that  angle  on  the  sextant  (neglect- 
ing the  index  error  if  it  is  small)  and  watch  the  two  selected 
objects  C  and  L,  holding  the  instrument  in  a  horizontal 
position.  When  the  two  objects  appear  in  the  horizon 
glass,  the  ship  is  close  to  the  circle  of  safety  Oi  a  a^,  and 
when  they  come  in  contact,  the  ship  is  on  that  circle;  once 
on  the  circle,  change  the  course  of  the  ship  so  that  the  two 
images  will  remain  in  contact  until  the  danger  is  passed. 
As  long  as  this  is  being  done,  the  ship  will  be  on  the  circle 
of  safety  ai  a  ao,  since  the  angles  C  ai  L,  C  a  L,  and  C  a2  L 
are  all  equal,  being  angles  in  the  same  segment.  If  the 
angle  increases,  the  ship  is  on  the  inside  of  the  circle  of 
safety  and  consequently  nearer  the  danger  than  is  desirable, 
if  it  becomes  smaller,  the  ship  is  outside  of  the  ^-mi.  limit. 
When  circumstances  permit  the  selection  of  a  vertical 
and  a  horizontal  danger  angle  the  latter  should  always  be 
preferred  as  being  more  reliable,  because  much  larger,  than 
the  former. 

NOTES  RELATING  TO  THE  USE  OF  FOREIGN  CHARTS 

Meridians  Used  on  Foreign  Charts. — On  English,  Dutch, 
Scandinavian,  Russian,  Austrian,  and  American  charts, 
Greenwich  meridian  is  used  as  the  first,  or  prime,  meridian. 
On  French  charts,  the  meridian  passing  through  Paris  is 
used;  its  long,  is  2°  20'  15"  or,  0''  9"  218  east  of  the  Greenwich 
meridian.  The  meridian  of  San  Fernando,  used  on  Spanish 
charts,  is  in  long.  6°  12'  24",  or  0^  24"  49.6'  west  of  the 


118 


TERRES  TRIAL  NA  VIGA  TION 


Greenwich  meridian.  On  Portuguese  charts,  the  meridian 
passing  through  the  Marine  Observatory,  Lisbon,  is  used; 
its  long,  is  9°  11'  10",  or  O*'  36"^  44.7^  west  of  Greenwich. 
The  meridian  of  Pulkowa  Observatory,  St.  Petersburg, 
which  is  sometimes  used  on  Russian  charts,  lies  in  long. 
30°  19'  40",  or  2^  l"  18. 7>  east  of  Greenwich.  The  observa- 
tory of  Naples,  the  meridian  of  which  is  sometimes  used  on 
Italian  charts,  is  in  long.  14°  15'  7.3"  or,  0^  57"  0.5»  east  of 
Greenwich. 

NAMES  OF  LIGHTS  USED  ON  CHARTS  IN  DIFFERENT 
LANGUAGES 


English 

German 

French 

Italian 

Fixed  light 

Festes  feuer 

Feu  fixe 

Luce  fissa 

Fixed  and 
flashing  light 

Festes  feuer 
mit  BHnken 

Feu  fixe  a 
Eclats 

Luge  bianca 
a  splendori 

Revolving 
light 

Blinkfeuer 

Feu  tournant 
et  feu  a  echpses 

Luge  a 
splendori 

Quick  flashing 
light 

Funkelfeuer 

Feu  scintillant 

Luge 
scintillante 

Group  flashing 
light 

Gruppen- 
blinkfeuer 

Feu  k  eclats 

Luge  a  gruppi 
di  splendori 

Flashing  light 

Blitzfeuer 

Feu  cliquotant 

Luge 
scintillante 

Intermittent  or 
occulting  light 

Unter- 
brochenes  feuer 

Feu 
intermittent 

Luge 
intermittente 

Alternating 
light 

Wechselfeuer 

Feu  altematif 

Luge 
alternate 

For  symbols  and  abbreviations  in  use  on  the  pfficial  charts 
of  the  principal  maritime  nations,  the  reader  should  consult 
U.  S.  Hydrographic  Office  Publication  No.  121. 

Soundings  on  Foreign  Charts. — In  order  to  facilitate  the 
reduction  of  measurements  of  depth  given  on  foreign  charts 
to  English  standards,  the  following,  may  prove  useful. 


CELESTIAL  NAVIGATION  119 

Feet  Fathoms 

Danish  and  Norwegian Fawn     =  6.175  =  1.029 

Dutch  (old) Vadem  =  5.575  =     .929 

Dutch  (recent) Elle        =  3.281  =     .547 

French .Metre     =  3.281  =     .547 

Portuguese   Braca     =  6.004  =  1.000 

Prussian Faden    =  5.906  =     .984 

Spanish Metro     =  3.281  =     .547 

Swedish Famn    =  5.843  =     .974 

Russian,  equal  to  English  feet  and  fathoms. 

The  Spanish,  Portuguese,  and  Italian  Metro,  and  the 
Dutch  Elle  and  French  Metre  are  identical. 


CELESTIAL  NAVIGATION 

ASTRONOMICAL  TERMS  AND   DEFINITIONS 

Angular  distance  is  the  arc  contained  between  lines  drawn 
from  two  objects  toward  an  observer;  it  must  not  be  con- 
founded with  the  actual  linear  distance  between  the  objects; 
it  is  expressed  in  angular  measure  and  must  necessarily  be 
the  same  at  any  points  along  the  lines  at  equal  distance 
from  the  observer. 

Celestial  sphere  is  the  apparent  spherical  surface,  called  the 
sky,  that  surrounds  the  earth  on  every  side  and  to  which  all 
the  heavenly  bodies  seem  to  be  attached.  The  center  of  the 
celestial  sphere  is  regarded  to  be  at  the  center  of  the  earth. 

Celestial  Poles. — The  position  of  the  celestial  poles  is 
indicated  by  the  prolongation  of  the  axis  of  the  earth. 

Celestial  equator  is  the  great  circle  formed  by  the  plane  of 
the  earth's  equator  extended  toward  the  celestial  sphere; 
it  is  also  known  as  the  equinoctial. 

Ecliptic  is  the  great  circle  that  the  sun's  apparent  path 
describes  on  the  celestial  sphere.  It  is  inclined  to  the 
equator  at  an  angle  that  may  be  assumed  to  be  23°  27', 
crossing  it  in  two  opposite  points  called  the  equinoctial 
points.  The  point  at  which  the  sun  passes  from  south  to 
north  of  the  equinoctial  is  called  the  first  point  of  Aries,  or 
vernal  equinox,  while  the  opposite  point  is  called  the  autumnal 
equinox. 


120 


CELESTIAL  NAVIGATION 


Solstitial  points  are  those  points  of  the  ecliptic  that  are 
farthest  north  or  south  from  the  equator  and  situated 
therefore  midway  between  the  equinoctial  points. 

Obliquity  of  the  ecliptic  is  the  angle  between  the  ecliptic 
and  the  celestial  equator. 

Celestial  meridians  are  great  circles  passing  through  the 
celestial  poles  and  intersecting  the  celestial  equator  at 
right  angles.  They  are  identical  to  meridians  of  the  earth 
extended  toward  the  celestial  sphere.  The  celestial  meridian 
most  freqtiently  in  use  by  navigators  passes  through  the 
zenith,  and  consequently  through  the  north  and  south  point 
of  the  horizon,  as  shown  in  Fig.  1.  It  is  known  as  the 
meridian.  Celestial  meridians  are  also  called  hour  circles, 
because  the  arcs  of  the  equator  intercepted  between  them  are 
used  as  measures  of  time. 

z 


Jiuiionnl       Horizon 

Fig.  1 

Diurnal  motion  is  the  apparent  daily  motion  of  the 
heavenly  bodies  from  east  to  west  caused  by  the  rotation 
of  the  earth  on  its  axis. 

Zenith  is  the  point  Z,  Fig.  1 ,  of  the  celestial  sphere  that  is 
vertically  above  the  head  of  an  observer.  The  zenith  of 
any  point  on  the  surface  of  the  earth  is  indicated  by  the 
direction  of  the  plumb-line  at  that  point. 

Rational  horizon  is  the  great  circle  whose  plane  is  per- 
pendicular to  the  zenith  and  passes  through  the  center  of 
the  earth. 

Sensible,  or  true,  horizon  is  the  plane  passing  through  the 
point    where    the    observer    stands;    it   is   perpendicular   to 


CELESTIAL  NAVIGATION 


121 


the  observer's  zenith  and  consequently  parallel  with  the 
rational  horizon,  as  shown  in  Fig.  2. 

Sea  horizon  is  the  apparent  boundary  between  the  sky 
and  the  sea,  forming  a  circle  at  the  center  of  which  the 
observer  stands. 

Verticals. — Circles  of  altitude,  or  verticals,  are  great 
circles  that  pass  through  the  zenith  intersecting  the  rational 
horizon  at  right  angles. 

Prime  vertical  is  the  vertical  at  right  angles  to  the  merid- 
ian; it  passes  through  the  east  and  west  point  of  the  horizon, 
as  shown  in  Fig.  1. 

True  altitude  is  the  angular  distance  of  a  celestial  body 
from  the  rational  horizon;  it  is  measured  along  the  vertical 
passing  through  the  body,  as  shown  in  Fig.  1. 


Sensible                 ^ 

a 

Horixon. 

^^y^^ji 

^Hx^^. 

^^^ 

JSatibnalt 

1  1  fforixon. 

% 

§ 

^ 

^ 

f         . 

Fig.  2 

Observed  altitude  is  the  distance  of  a  celestial  body  above 
the  sea  horizon,  expressed  in  angular  measure. 

Zenith  distance  is  the  distance  of  the  observed  body  from 
the  observer's  zenith;  it  is  the  complement  of  the  altitude. 

True  azimuth  is  the  arc  of  the  horizon  intercepted  between 
the  true  north  or  south  and  the  vertical  passing  through 
the  body;  it  is  measured  from  north  or  south  toward  east 
or  west  and  may  be  of  any  value  from  0°  to  180°. 


122' 


CELES  TIA  L  NA  VIGA  TION 


Compass  azimuth  is  the  azimuth  measured  by  the  ship's 
compass;  the  difiference  between  the  true  and  compass  azi- 
muths is  the  total  error  of  the  compass. 

True  amplitude  is  the  complement  of  the  true  azimuth; 
it  is  measured  along  the  horizon  from  the  prime  vertical 
toward  north  or  south. 

Compass  amplitude  is  the  amplitude  measured  by  the 
ship's  compass;  it  is  affected  by  variation  and  deviation. 

Hour  angle  is  the  angle  at  the  pole  subtended  between 
the  meridian  and  the  hour  circle  passing  through  a  celestial 
body.  It  is  measured  from  the  meridian  westwards  and 
may  be  of  any  magnitude  from  O*"  to  24^. 


Equator 


Fig.  3 

Declination  is  the  angular  distance  of  a  body  north  or 
south  frorri  the  celestial  equator;  it  is  measured  by  the  arc 
of  the  hour  circle  passing  through  the  object  and  intercepted 
between  it  and  the  equator. 

Polar  distance  is  the  distance  of  a  celestial  body  from  the 
nearer  pole;  it  is  measured  by  the  arc  of  the  hour  circle 
intercepted  between  the  pole  and  the  body.  The  polar 
distance  is,  therefore,  the  complement  of  the  declination,  as 
shown  in  Fig.  3. 

Parallels  of  declination  are  small  circles  parallel  to  the 
celestial   equator. 

Right  ascension  is  the  arc  of  the  celestial  equator  measured 
eastwards  from  the  vernal  equinox  to  the  hour  circle  passing 


CELESTIAL  NAVIGATIOS  123 

through  a  celestial  body.  It  is  reckoned  from  O*"  to  24''. 
Thus,  in  Fig.  3,  the  right  ascension  of  the  star  5  is  about  Z^, 
while  that  of  the  star  s'  is  about  \b^.  The  approximate 
position  of  the  vernal  equinox  in  the  sky  is  easily  fixed  any 
clear  night  by  following  an  imaginary  line  from  Polaris  that 
passes  through  or  very  near  the  stars  Alpha,  Andromeda, 
and  Algenib.  At  a  distance  of  90°  from  Polaris,  along  that 
line,  is  the  vernal  equinox.  Hence,  the  right  ascension  of 
all  stars  to  the  left  of  that  line  is  small,  while  that  of  stars 
to  the  right  is  large. 

Annual  parallax  is  the  greatest  angle  subtended  at  a  star 
by  the  radius  of  the  earth's  orbit.  The  parallax  of  only  a 
few  stars  has,  as  yet,  been  determined,  and  in  no  case  does 
it  amount  to  as  much  as  1  sec. 

Parallax  in  altitude  is  the  angle  subtended  by  a  line  joining 
a  celestial  body  with  the  point  of  observation  and  a  line 
joining  the  same  body  with  a  certain  point  of  reference, 
such  as  the  center  of  the  earth.  A  correction  for  parallax 
is  used  when  correcting  observed  altitudes,  and  is  always 
additive.  This  correction  is  maximum  when  the  body  is 
near  .the  horizon  and  vanishes  on  approaching  the  zenith. 

Dip  is  the  angular  distance  between  the  sensible  horizon 
and  a  line  drawn  from  the  observer's  eye  to  the  sea  horizon, 
as  shown  in  Fig.  2.  The  amount  of  dip  depends  on  the 
height  above  the  surface  of  the  sea,  increasing  as  the  height 
of  the  eye  increases.  The  correction  for  dip  is  always 
subtractive. 

Refraction  is  the  downward  deflection  of  a  ray  of  light 
on  entering  the  atmosphere  of  the  earth,  causing  a  celestial 
body  to  appear  higher  than  it  kctually  is.  It  is  least  in 
high  altitudes,  and  increases  toward  the  horizon.  The 
correction  for  refraction  is  subtractive. 

Transit,  or  transition,  is  the  passage  of  a  celestial  body,  such 
as  a  star,  across  the  meridian  of  a  certain  place,  either  above 
or  below  the  pole ;  it  is  identical  to  meridian  passage  and  cul- 
mination. Thus,  when  the  sun  reaches  its  highest  altitude 
on  any  day,  it  is  said  to  be  in  culmination  or  transition. 

Circles  of  celestial  longitude  are  great  circles  perpendicular 
to  the  ecliptic  and  passing  through  the  poles  of  the  ecliptic. 


124  CELESTIAL  NAVIGATION 

Celestial  latitude  is  the  angular  distance  of  a  star  or  planet 
from  the  ecliptic  measured  along  the  circle  of  longitude  that 
passes  through  the  object. 

Celestial  longitude  is  the  arc  of  the  ecliptic  measured 
eastwards  from  the  vernal  equinox  to  the  circle  of  longitude 
passing  through  a  celestial  object. 

The  Solar  System. — A  body,  like  the  earth,  that  performs  a 
circuit  about  the  sun,  is  called  a  planet.  A  smaller  body,  like 
the  moon,  that  revolves  about  a  planet,  is  called  a  satellite  of 
tliat  planet.  The  sun,  planets,  and  satellites  constitute  what 
is  called  the  solar  system.  Including  the  earth,  there  are 
eight  known  planets,  which  are  divided  into  two  classes — 
interior  and  exterior  planets.  Interior  planets  are  those 
whose  orbits  lie  within  that  of  the  earth;  viz..  Mercury  and 
Venus;  exterior  planets  are.  those  whose  orbits  are  greater 
than  that  of  the  earth  and,  consequently,  lie  outside  of  it; 
they  are.  Mars,  Jupiter,  Saturn,  Uranus,  and  Neptune.  The 
principal  elements  of  the  solar  system  are  given  in  the  table . 

Between  the  orbits  of  Mars  and  Jupiter,  there  are  a  num- 
ber of  small  planets,  called  asteroids,  of  which  at  present 
about  384  are  known ;  they  are  supposed  to  be  the  fragments 
of  a  burst  planet.  A  number  of  these  small  planets  have 
not  been  observed  since  their  discovery  and  are  practically 
lost.  Hence,  it  is  sometimes  a  matter  of  doubt,  until  cer- 
tain elements  have  been  computed,  whether  a  supposed 
new  pTanet  is  really  new  or  only  an  old  one  rediscovered. 
All  the  exterior  planets  are  attended  by  moons,  similar  to 
ours,  that  move  around  them  in  the  same  direction  that 
the  planets  themselves  revolve  around  the  sun.  Th3  only 
exceptions  are  the  satellites  of  Uranus  and  Neptune,  which 
revcilve  in  the  opposite  direction. 

Conjunction. — A  planet  is  said  to  be  in  conjunction  with 
another  body  when  both  lie  on  the  same  line,  or  is  seen  in 
the  same  direction  in  the  heavens.  In  the  case  of  interior 
planets  this  conjunction  is  of  two  kinds:  the  one  when  the 
planet  is  between  the  earth  and  the  sun,  called  inferior 
conjunction;  and  the  other  when  at  the  opposite  pomt  oi 
its  (irbit,  with  the  sun  between  the  planet  and  the  earth, 
called  superior  conjunction. 


CELESTIAL  NAVIGATION 


125 


Gravity 
at  Surface 
Earth  =  1 

s§§ 

(N  (N  X  O  t^  <N '- <N  (N 

h 

1.310,000 

.05 

.92 

1.00 

.15 

1 ,309 .  00 

721 .00 

65 .  00 

85 .  00 

Mean 

Diameter 

Miles 

866.400 

3,030 

7,700 

7,910 

4,230 

86,500 

71,000 

31.900 

34,800 

lis 

87.96 

224 . 70 

365.25 

686.95 

4,332.58 

10,759.22 

30,686.82 

60,181.11 

Mean 
Distance 
From  Sun 
Expressed 
in  Millions 
of  Miles 

c  w  X  >o  ro  o  C5  o 

CCXiOiThXXxS 
•-(•^Xt^t^ 

s 

2 

c 

11 

126  CELESTIAL  NAVIGATION 

Opposition. — A  planet  is  said  to  be  in  opposition  when 
the  earth  is  directly  between  it  and  the  sun,  at  which  time 
it  is  most  brilliant. 

Elongation  is  the  angle  formed  by  lines  connecting  the 
earth  with  a  planet  and  sun,  respectively. 

Quadrature. — Two  heavenly  bodies  are  said  to  be  in 
quadrature  when  they  are  half  way  between  conjunction 
and  opposition. 

Occultation. — The  moon,  in  her  orbital  motion,  often 
passes  before,  and  hides  from  a  spectator  on  the  earth,  certain 
of  the  fixed  stars,  and  occasionally  one  of  the  planets;  these 
occurrences  are  called  occultations. 

EXPLANATIONS    OF    TERMS    RELATING   TO    TIME 

Apparent  solar  day  is  the  interval  of  time  between  two 
successive  transits  of  the  sun  over  the  same  meridian; 
apparent  time  is  measured  by  the  hour  angle  of  the  true  sun. 

Mean  Sun. — The  intervals  between  the  successive  returns 
of  the  sun  to  the  same  meridian  are  not  exactly  equal,  owing 
to  the  varying  motion  of  the  earth  around  the  sun,  and  to 
the  obliquity  of  the  ecliptic,  and  for  this  reason  the  length 
of  the  apparent  solar  day  is  not  the  same  at  all  times  of  the 
year  and  cannot  be  measured  by  a  clock  whose  rate  is 
uniform.  To  avoid  the  irregularity  that  would  arise  from 
using  the  true  sun  as  the  measure  of  time,  a  fictitious  sun, 
called  the  mean  sun  has  been  devised,  which  is  supposed 
to  move  along  the  celestial  equator  with  a  uniform  velocity. 
This  mean  sun  is  supposed  to  keep,  on  the  average,  as  near 
the  real  sun  as  is  consistent  with  perfect  uniformity  of 
motion;  it  is  sometimes  in  advance  of  it,  and  sometimes 
behind  it,  the  greatest  deviation  being  about  16  min.  of  time. 

Mean  time,  which  is  perfectly  equable  in  its  increase,  is 
measured  by  the  motion  of  the  mean  sun.  The  clocks  in 
ordinary  use  and  chronometers  are  regulated  to  mean  time. 

Mean  solar  day  is  the  average,  or  mean,  of  all  the  apparent 
solar  days  in  a  year;  or,  the  interval  of  time  between  two 
successive  mean  noons. 

Equation  of  time  is  the  difference  between  apparent  and 
mean  time;  its  value  for  every  day  of  the  year  is  recorded 


CELESTIAL  NAVIGATION  127 

in  the  Nautical  Almanac.  By  means  of  the  equation  of 
time,  we  change  apparent  to  mean  time,  or  the  reverse, 
by  adding  or  subtracting  it  acording  to  directions  in  the 
Almanac. 

Sidereal  time  is  the  time  measured  by  the  daily  motion  of 
the  stars;  or  for  astronomical  purposes,  by  the  daily  motion 
of  that  point  in  the  equator  from  which  the  true  right 
ascension  of  the  stars  is  counted.  This  point  is  the  vernal 
equinox,  and  its  hour  angle  is  called  sidereal  time.  Astro-' 
nomical  clocks,  regulated  to  sidereal  time,  are  called  sidereal 
clocks. 

Sidereal  day  is  the  interval  between  two  successive  upper 
transits  of  the  vernal  equinoctial  point,  and  begins  when 
the  vernal  equinoctial  point  is  on  the  meridian.  It  is  about 
3  min.  and  56  sec.  shorter  than  the  mean  solar  day;  and  is 
divided  into  24  sid.  hr. 

Astronomical  Day. — When  mean  time  is  used  in  astro- 
nomical work,  the  day  begins  at  mean  noon  and  is  called 
the  astronomical  day;  astronomical  mean  time  is  reckoned 
continuously  up  to  24  hr. 

Civil  Day. — When  mean  time  is  used  in  the  ordinary 
affairs  of  life  it  is  called  civil  time  and  the  civil  day  begins 
at  midnight,  12  hr.  earlier  than  the  astronomical  day. 
Thus,  Jan.  9,  2  o'clock  a.  m.,  civil  time,  is  Jan.  8,  14  hr., 
astronomical  time;  and  Jan.  9,  2  o'clock  p.  m.,  civil  time, 
is  also  Jan.  9,  2  hr.,  astronomical  time.  The  rule  for  con- 
verting civil  time  into  astronomical  time  is  this:  If  the 
civil  time  is  marked  a.  m.,  take  1  from  the  date  and  add 
12  to  the  hours,  and  the  result  is  the  astronomical  time 
wanted;  if  the  civU  time  is  marked  p.  m.,  take  away  the 
designation  p.  m.,  and  the  astronomical  time  is  had  without 
further  change. 

To  change  astronomical  to  civil  time,  we  simply  write 
P.  M.  after  it  if  it  is  less  than  12  hr.  If  greater  than  12  hr., 
we  subtract  12  hr.  from  it,  increase  the  date  by  1,  and  write 
A.  M.  For  example,  Jan.  3,  23  hr.,  astronomical  time,  is 
Jan.  4,  11  o  clock  a.  m.,  civil  time. 

Local  mean  time  (L.  M.  T.)  is  the  mean  time  at  a  certain 
place  or  locality,  as,  for  example,  the  mean  time  at  ship;  at 


128  CELESTIAL  NAVIGATION 

no  time  can  the  mean  time  be  the  same  at  two  places  unless 
they  are  situated  on  the  same  meridian. 

Greenwich  date  (G,  D.)  is  the  local  mean  time  at  Green- 
wich shown  by  the  chronometer  and  with  proper  date 
appended;  the  Greenwich  date  should  be  expressed  astro- 
nomically. Chronometer  being  marked  up  to  12  hr.  only,  it 
cannot  always  be  decided,  especially  where  longitude  is 
large,  whether  the  Greenwich  mean  time  (G.  M.  T.)  is  more 
or  less  than  12  hr.  In  such  cases,  it  is  advisable  to  get  an 
approximate  value  of  the  G.  D.  by  applying  to  the  local 
time  the  hours  and  minutes  of  the  ship's  longitude,  adding 
if  in  west,  subtracting  if  in  east,  longitude.  In  case  the 
difference  between  this  approximation  and  the  time  by  the 
chronometer  is  nearly  12  hr.,  add  12  hr.  to  the  latter  and 
put  the  day  back  1,  if  necessary. 

Example. — The  local  time  at  a  ship  in  longitude  150"  30'  W 
is  5*^  40"'  p.  M.,  Dec.  16.  The  chronometer  indicates  2^  22™  10', 
its  error  on  G.  M.  T.  being  10™  50'  slow.     Find  G.  D. 

Solution. — Ship's  time,  Dec.  16=        5''  40" 

Long.  (W)  in  time=  +10''    2'" 

Approx.  G.  D.,  Dec.  16  = 


15b  42-» 

3h22"' 

10' 

-t-lO-" 

50' 

Chron.  = 

Error  = 

G.  M.  T.,  Dec.  16=       Sb  as-n 

Add=      12h 

G.  M.  T.  or  G.  D.,  Dec.  16=      15"  SS"" 
In  this  case  12''  must  be  added  to  the  time  indicated  by 
the  chronometer.     This  gives  the  G.   D.,  corresponding  to 
ship  time,  as  Dec.  16,  15''  SS-".     Ans. 

Notes  on  the  Correction  of  Altitudes. — The  altitude  of  a 
celestial  object,  as  measured  with  a  sextant,  is  called  the 
observed  altitude;  but  in  order  to  obtain  the  true  altitude 
some  or  all  of  the  following  corrections  must  be  applied: 
(1)  Index  error  of  the  sextant,  (2)  dip  of  the  horizon, 
(3)  refraction,  (4)  parallax,  (5)  semi-diameter.  The  cor- 
rection for  dip  and  refraction  are  taken  from  nautical 
tables;  parallax  of  the  sun  is  also  found  in  tables,  while  that 
of  the  moon  is  tabulated  in  the  Nautical  Almanac.     The 


CELESTIAL  NAVIGATION  129 

semi-diameter  of  the  sun  that  is  taken  from  the  Nautical 
Almanac  is  applied  according  to  what  limb  is  brought  in 
contact  with  the  horizon;  if  lower  limb  is  observed,  it  is 
additive;  if  upper  limb,  subtractive. 

In  correcting  altitudes,  it  should  be  remembered  that 
the  observed  altitude  is  that  read  off  the  sextant.  When 
this  has  been  corrected  for  index  error,  dip,  and  semi- 
diameter,  the  result  is  the  apparent  altitude  of  the  center, 
and  the  application  to  this  of  the  corrections  for  refraction 
and  parallax  produces  the  true  altitude  of  the  center  of  the 
observed  body,  as  if  the  observation  had  been  made  at  the 
center  of  the  earth  and  the  altitude  had  been  measured 
from  the  rational  horizon. 

The  observed  altitude  of  a  star  has  to  be  corrected  only  for 
index  error,  dip,  and  refraction.  When  an  artificial  horizon 
is  used,  apply  index  error  to  the  double  altitude  read  off  the 
sextant,  divide  by  2,  and  apply  the  other  corrections  as  usual, 
except  that  for  dip.  When  correcting  altitudes  of  the  sun, 
use  refraction  and  parallax  corresponding  to  the  apparent 
altitude  of  the  upper  or  lower  limb;  for  altitude  of  the  moon, 
use  the  apparent  altitude  of  the  moon's  center. 

Since  the  value  of  dip  depends  on  the  height  of  the  eye 
above  surface  of  the  sea.  it  is  advisable  always  to  ascertain 
beforehand  the  exact  vertical  distance  from  water-line  to 
the  bridge,  or  other  place  usually  occupied  by  observer, 
when  measuring  altitudes.  And  due  allowance  should  be 
made  for  any  reduction  or  increase  in  this  vertical  distance 
when  ship  is  loaded,  or  light,  or  when  having  a  considerable 
list  to  either  side.  

LATITUDE  DETERMINATIONS 
Meridian  Altitude  of  the  Sun. — The  measurement  shovild 
begin  a  short  time  before  noon,  say  10  or  15  min.  The 
altitude  will  increase  gradually  until  apparent  noon,  when 
it  will  stop  and  begin  to  decrease.  The  highest  altitude 
attained  is  the  desired  meridian  altitude.  Apply  to  this 
observed  altitude  the  necessary  corrections,  and  subtract 
the  true  altitude  thus  found  from  90°.  The  result  is  the 
zenith  distance,  which  is  named  opposite  to  the  direction 


130  CELESTIAL  NAVIGATION 

the  observer  is  facing  when  measuring  the  altitude.  Find, 
from  the  Nautical  Almanac,  the  sun's  declination  and  correct 
it  for  the  G.  D.  Take  the  algebraic  sum  of  the  declination 
and  zenith  distance,  and  name  it  the  same  as  the  larger 
quantity.     The  result  is  the  required  latitude. 

Example.— On  Sept.  23,  1904,  in  longitude  11°  45'  W,  by 
dead  reckoning,  the  observed  meridian  altitude  of  the  sun's 
lower  limb  was  33°  37'  40",  the  observer  facing  south;  index 
error  =  + 1'  40";  height  of  eye  =  23  ft.     Find  the  latitude. 

Solution.— L.  App.  T.  Sept.  23  =  0'>    C"  0^ 
Long.  (W)  in  time  =  0''  47™  0» 


Corr. 

Decl. 

for  47'" 

G.  D.  Sept. 
=  S0°0'  11.6" 
+  46.7" 

23  = 

-.Qh  47m  OS 

Change  in  I*" 

=  58.4" 
X.8h 

Con 

-.  Decl. 

=  S  0°0'58.3" 
Obs.  Mer.  Alt. 
L  E. 

=  33 

Corr.  = 
°  37'  40" 
+  1'  40" 

=  46.72" 

33°  39'  20" 

Dip  =       -4' 42" 

33°  34'  38" 

S.  D.=     +15' 59" 


App.  Alt.  =  33°  50' 37" 
Ref.=       -1'26" 


Parallax 

= 

+  0' 

7" 

True  Mer.  Alt. 

=  33° 
90° 

49' 
0' 

18" 
0" 

Z.  D. 

Decl. 

Latitude 

=  56° 
=   0° 
=  56° 

10' 
0' 
9' 

42" 
58" 
44" 

N 
S 

"n 

Ans. 

In  this  case,  the  bearing  of  the  sun  being  south,  the  zenith 
distance  is  north;  the  declination  being  south,  the  latitude 
is  therefore  equal  to  the  difference  between  the  two,  having 
tlie  same  name  as  the  larger  quantity. 

Meridian  Altitude  of  a  Star. — Select  a  bright  star  that  is 
near  and  about  to  cross  your  meridian.  Be  sure  that  the 
star  selected  is  identified  without  doubt.     Find  to  the  nearest 


CELESTIAL  NAVIGATION  131 

minute  the  local  apparent  time  of  its  meridian  passage,  by 
subtracting  from  the  star's  right  ascension  the  right  ascen- 
sion of  the  sun,  and  thence  the  correspdnding  mean  time. 
Be  ready  with  the  sextant  a  few  minutes  before  that  time 
and  proceed  exactly  as  in  the  case  of  observing  the  sun. 

Example. — On  Oct.  19,  1904,  an  opportunity  presented 
itself  to  observe  the  meridian  altitude  of  the  star  Sirius 
(a  Canis  Majoris);  the  altitude  when  measured  was  45°  34 
20",  the  observer  facing  south;  index  error  =  -2'  20";  height 
of  eye  =  23  ft.     Find  the  latitude. 

Solution. — For  approximate  time  of  meridian  passage. 
R.  A.  (  +  24h)=30i'  41'» 
R.  A.' Sun  =  13^35^ 
L.  App.  T.  =  17h    G"" 
Eq.  of  T.  =_-L5^ 
L.  M.  T.  =  16h  Si-"  p.  M. 
Approx.  L.  M.  T.  of  passage  =    4''  51™  a.  m. 

Obs.  Mer.  Alt.  =  45°  34'  20" 
I.  E.=       -2' 20" 


45°  32'    0" 
Dip  =       -  4'  42" 


45°  27'  18" 
Ref .  =       -  0'  56" 


True  Alt.  =  45°  26'  22" 
90°    0'    0" 


Z.  D.  =  44°33'  38"  N 
Decl.  =  16°35'    5"  S 


Latitude  =  27°  58' 33"  N     Ans. 

The  star's  declination,  which  is  practically  constant,  is 
taken  directly  from  the  catalog  of  fixed  stars  in  the  Nau- 
tical Almanac. 

Meridian  Altitude  of  the  Moon. —  Find,  from  the  Nautical 
Almanac,  the  mean  time  of  the  moon's  meridian  passage  at 
Greenwich,  If  your  local  time  is  P.  m.,  take  it  out  for  the 
given  date;  if  a.  m.,  for  the  day  preceding.  Apply  to  it  a 
correction  equal  to  the  hourly  difference  multiplied  by  the 
longitude  in  time,  adding  this  correction  when  longitude  is 


132  CELESTIAL  NAVIGATION 

west,  but  subtracting  it  wher^  east;  the  result  is  the  local 
time  of  transition.  Then  find  the  corresponding  G.  M.  T. 
by  applying  the  longitude  in  time.  For  the  G.  D.  thus 
found,  correct  the  moon's  semi-diameter  declination  and 
parallax  as  shown  in  the  example  that  follows:  Measure 
the  altitude  at  the  proper  time  and  reduce  it  to  true,  whence 
the  latitude  is  found  as  usual. 

Example. — On  Aug.  22,  1904,  in  the  evening,  a  meridian 
altitude  of  the  moon's  lower  limb  measured  in  an  artificial 
horizon  was  61°  46'  30",  the  observer  facing  south;  index  error 
of  sextant  =  +1'  30" ;  long.  =  75°  45'  W.    Find  the  latitude. 

Solution. — Find,  first,  the  local  time  of  meridian  passage  and 

the  requisite  elements  of  the  moon  in  the  Nautical  Almanac. 

Mer.  pass.  Aug.  22  =     9^40.5'°  Change  in  1^  =  2"' 

Corn  for  long.  =  +      lO-^  X5*' 

L.  M.  T.  of  pass.=      9^^  50.5°^  p.  m.  Corr.  =  10°' 

Long,  in  time=  +5"^    3™ 
G.  M.  T.  Aug.  22  =   141'  53.5m 

Moon's  S.D.  at  midnight  =  14'  56"  (nearly) 
Corr.  for  Alt.  =       +7" 
Corr.  S.  D.  =  15'    3" 

Hor.  Par.  at  midnight  =  54'  42" 

Decl.  at  14»>  Aug.  22  =  S  16°  43'  28"  Change  1^  =  4" 

Cor.  for  53.5'"=  -3'  34"  X53.5'° 


Corr.  Decl.  =  S  16°  39'  54"  214.0" 

Obs.  double  Alt.  =  61°  46'  30"  Corr.  =3'  34" 

I.  E.=       +1'30" 

2)61°  48     0" 

Obs.  Mer.  Alt.  =  30°  54'    0" 

S.  D.=  +    15'    3" 


App.  Alt.  center  =  31°    9'    3" 
Par.  Ref.=     +45'  13" 


True  Mer.  Alt.  =  31°  54'  16" 


CELESTIAL  NAVIGATION  133 

True  Mer.  Alt.  =  31°  54'  16" 
90°    0'    0" 


Z.  D.  =  58°    5'  44"  N 
Decl.  =  16°39'  54"  S 


Latitude  =  41°  25' 50"  N     Ans. 

The  correction  for  parallax  and  refraction  is  taken  from 
I.  C.  S.  Nautical  Tables,  page  170,  or  from  Table  24,  Bow- 
ditch. 

Ex-Meridian  of  the  Sun. — Measure  an  altitude  within 
1  hr.  of  noon  (either  p.  m.  or  A.  M.),  and  note  the  chronometer 
time  at  instant  of  observation.  From  the  time  thus  noted, 
find  the  hour  angle,  H.  A.,  which  is  equal  to  local  apparent 
time,  and  express  it  in  degrees,  minutes,  and  seconds. 
Reduce  the  observed  altitude  to  true,  and  correct  the  decli- 
nation for  G.  M.  T.  From  the  data  now  at  hand,  calculate 
two  quantities  that  we  will  designate  M  and  N.  Find  the 
value  of  M  by  formula: 

Tan  M  =  sec  H.  A.Xtan  Decl. 
and  that  of  A'^  by  formula: 

Cos  A'  =  sin  A/Xsin  Alt.Xcosec  Decl. 

Name  M  the  same  as  declination  and  N  the  same  as 
zenith  distance.  If  they  have  the  same  name,  take  their 
sum;  if  of  different  names,  subtract  the  smaller  from  the 
larger.  The  result  is  the  latitude,  which  is  named  the  same 
as  the  larger  quantity. 

Example. — On  June  8,  1904,  in  long.  60°  15'  W.  the  sun 
being  obscured  by  clouds  at  noon,  an  altitude  of  the  lower 
limb,  observed  at  about  12.40  p.  m.,  was  found  to  be  78° 
33'  40",  the  observer  facing  south.  At  the  instant  of  measur- 
ing the  altitude,  the  chronometer  indicated  4^  46™  25',  its 
error  on  G.  M.  T.  being  1"  55^  fast;  index  error=  —3'  40"; 
height  of  eye  =  20  ft.     Required  the  latitude. 

Solution. — 

Chron.  =    '^^  46'°  25' 
Error  (fast)  =        - 1-^  55' 


G.  D.,  June  8=   4b  44>"  30« 


134 


CELESTIAL  NAVIGATION 


G.  D.,  June  8=   4^  44°>  30» 
Long.  (W)  in  time  =   4»'    I'"    0» 


L.  M.  T.=   0»>43°>30« 
Eq.  ofT.=       +1°' 13' 

L.  App.  T.=   Oh  44'°  43^ 
Or.  hour  angle  =  11°  10'  45" 

Eq.  of  T.  =  l"  15.5' 
Corr.  for  4.7»'=    -  2.2' 

Eq.  of  T.  =  l'°  13.3'  (  +  ) 

Change  in  lh  =  0.47' 
4.7h 

2.209' 

Decl.  =  N22°50'8.5" 
Corr.  for  4.7^=            +1' 4.3" 

Change  in  lh  =  13.68" 
4.7»> 

Ded.  =  N22°51'  12.8" 

9576 
5472 

Obs.  Alt.  =  78°  33'  40" 
I.  E.=       -3' 40" 


64.296" 


Dip 

78°  30' 
=       -4' 

0" 
23" 

.  D. 

78°  25' 
=     +15' 

37" 

47" 

Par. 

78°  41' 
=       -0' 

24" 
10" 

True  Alt.  =  78°  41'  14" 
The  true  altitude  being  found,  calculate  the  quantity  M 
and  A^  according  to  formulas  given;  thus, 


Tan  M  =  Sec  H.  A.  X  tan  Decl. 


sec  11°  10'  45"=    .00832 
tan  22°  51'  12"  =  9.62475 


tan  M  =  9.63307 
A/ =  23°  15' 


CosA^  =  sin  MX  sin  Alt. 
X  cosec  Decl. 

sin  23°  15' =  9. 59632 

sin  78°  41'  14"  =  9. 99147 

cosec  22°  51'  12"=    .41075 

Cos  A/ =  9. 99854 

A^  =  4°42' 


Lat.  =  M  +  N  =  23°  15' +  4°  42' =  27°  57'  N.     Ans. 


CELESTIAL  NAVIGATION  135 

LONGITUDE  DETERMINATIONS 

Time  Sight  of  the  Sun. — Measure  an  altitude  of  the  sun  in 
the  forenoon  or  afternoon  when  it  bears  nearly  east  or  west, 
and  note  the  corresponding  time,  either  directly  on  the 
chronometer  or  by  a  watch  previously  compared  with 
the  chronometer.     The  altitude  should  not  be  less  than  15°. 

Correct  the  chronometer  time  for  error  and  accumulated 
rate;  the  result  will  be  the  G.  M.  T.,  or  G.  D.,  at  the  instant 
of  observation.  Reduce  the  observed  altitude  to  true  by 
applying  the  usual  corrections.  Compute  the  latitude  of 
the  ship  by  dead  reckoning  from  the  last  observation  up  to 
the  time  of  taking  the  sight.  Take  out  the  equation  of  time 
and  correct  it  for  the  G.  D.  Similarly,  correct  the  sun's 
declination  for  the  G.  D.,  and  find  the  polar  distance  {p) 
as  follows:  If  latitude  and  declination  have  the  same  name, 
^  =  90°-decl.;  if  of  different  name,  ^  =  90°  +  decl.  Then 
calculate  the  hour  angle  by  the  formula 

Sin  i  H.  A.  =  "Vcosec  p  sec  /  cos  5  sin  iS-d) 
in  which  p  =  polar  distance ; 
/  =  latitude; 
a  =  true  altitude ; 
5  =  half  sum  of  a,  p,  and  /. 

In  other  words,  calciilate  the  hour  angle  by  the  given 
formula,  adding  the  log  cosec  p,  log  sec  /,  log  cos  S,  and  log 
sin  (S  —  a).  The  sum  divided  by  2  is  the  log  sine  for  t-hour 
angle.  If" the  observation  is  made  in  the  forenoon,  take  out 
the  corresponding  local  apparent  time  from  a.  m.  column  in 
the  tables;  if  made  in  the  afternoon,  from  the  p.  m.  column. 

The  local  apparent  time  having  been  determined,  the 
corresponding  local  mean  time  is  found  by  applying  the 
equation  of  time  according  to  its  sign.  The  difference 
between  L.  M.  T.  and  the  G.  M.  T.,  reduced  to  degrees, 
minutes,  and  seconds,  will  be  the  required  longitude.  If 
G.  M.  T.  is  greater  than  L.  M.  T.,  the  longitude  is  west;  if 
the  L.  M.  T.  is  greater  than  G.  M.  T.,  the  longitude  is  east. 

Example. — On  Jan.  17,  1904,  at  about  3.50  in  the  after- 
noon an  altitude  of  the  sun's  lower  limb  measured  37°  7'  40"; 
index  error=  —2'  30";  height  of  eye  =  16ft.;  at  instant  of 
observation  the  chronometer  indicated  7^  26™  478,  its  error 


136  CELESTIAL  NAVIGATION 

on  G.  M.  T.  being  2™  43'  slow;  lat.,  by  dead  reckoning,  is 
46°  30'  S.     Find  the  longitude. 

Solution.— Chron.,  Jan.  17  =  7''  26"  47» 
Error  ( slow)  =     +2°>  43- 

G.  M.  T.  Jan.  17  =  7'' 29"' 30»  p.  m. 

Decl.  =  S  20°  57'  42.9"  Change  in  1''=   28.51" 

Corr.=  -3' 33.8"  X7.5'' 


Decl.  =  S20°54'    9.1"  213.825 

90°    0'       0"  3'  33.8" 


P.  D.  =  69°    5'     51* 


Eq.  of  T.=   9"  53.64'  Change  in  li'  =  .86' 

Corr.=       +6.45'  X7.5'' 


Eq.  of  T.  =  10°'0.09'+  6.450* 

Obs.  Alt.  =   37°    r  40 
I.  E.=         -2' 30" 


37°    5'  10" 
Dip=         -3' 55" 


37°    1'  15" 
S.  D.=       +16' 17" 


37°  17'  32" 


.  and  Par.  =         - 1'    9" 

a=   37°  16' 23" 

p=   69°    5' 51" 

cosec=     .02956 

/=   46°  30'    0" 

sec=     .16219 

2)152°  52'  15" 

5=   76°  26'    7" 

cos=   9.37028 

S-a=   39°    9' 44" 

sin=   9.80039 

2)19.36242 
Sini  H,  A.=   9.68121 
L.  App.  T.=3''49°'28» 
•f  lO-"    0' 
L.  M.  T.  Jan.  17  =  3"'  59'"  28'  p.  m. 
G.  M.  T.  Jan.  17  =  7"  29""  30»  p.  m. 
Diff.  =3''  30'»    2» 
Long.  =  52°  30'  30"  W.      Ans. 


CELESTIAL  NAVIGATION  137 

Time  Sight  of  a  Star. — Select  a  bright  star  bearing  nearly- 
east  or  west;  measure  its  altitude  and  note  the  chronometer 
time  at  instant  of  observation.  Reduce  the  G.  M.  T.  into 
G.  S.  T.  by  adding  the  right  ascension  of  the  mean  sun  to 
G.  M.  T.,  as  shown  in  the  example  that  follows:  Correct 
the  altitude  as  usual  and  find,  from  the  Nautical  Almanac, 
the  star's  right  ascension  and  declination.  Calculate  the 
hour  angle  in  exactly  the  same  way  as  for  the  sun,  but  use 
only  the  p.  m.  column  of  the  tables  in  finding  the  hour  angle. 

If  the  hour  angle  is  east  (or  when  the  observed  star  is  to 
the  east  of  the  observer's  meridian),  subtract  it  from  the 
star's  right  ascension;  if  the  hour  angle  is  west  (or  the  star 
is  west  of  the  meridian),  add  it  to  the  star's  right  ascension. 
The  resvilt  will  be  the  right  ascension  of  the  observer's 
meridian,  or  the  L.  Sid.  T.  The  difference  between  this 
time  and  G.  Sid.  T.,  reduced  to  degrees,  minutes,  etc.  is  the 
required  longitude. 

Example.— On  Oct.  18,  1904,  at  about  2»'  SO-"  a.  m..  the 
observed  altitude  of  the  star  Sirius  (a  Canis  Majoris)  when 
east  of  the  meridian  was  53°  52'  40";  index  error  =  +2'  43"; 
height  of  eye  =  22  ft.  The  time  indicated  by  chronometer 
was  ll''  ?•"  21^  its  error  on  G.  M.  T.  being  3"  22^  fast;  long, 
estimated  at  50°  E;  lat.  =  15°  14'  S.     Find  the  longitude. 

Solution. — First,  find  the  approximate  G.  D.;  thus, 
Approx.  L.  M.  T.  Oct.  17=    14*'  SO-" 
Long.  (E)  in  time  =-3"  20" 
Approx.  G.  D.  Oct.  17=   ll''  10" 

Then,  from  reading  of  chronometer  get  the  G.  M.  T.,  or 

G.  D.  and  the  corresponding  sidereal  time  at  Greenwich;  thus, 

Chron.  =  lli'    7"  2P     S.  T.  G.  M.  N.  =  13b  42™  13.9, 


Error  (fast)  =       -3"22» 
M.T.Oct.  17  =  11'^    3"  59^ 

^         fforll" 
C°"-|for4" 

1™  48.4« 
.7* 

R.  A.  M.  S.  =  13M4»    3« 
S.T.  Oct.  18=   0''48"    2» 
*Decl.  =  Sl6°35'    5" 
90°    0'    0" 

R.  A.  M.  S.= 

=  13M4"       38 

♦P.  D.=     73°  24' 5 
*R.  A.  =  6"  40"  55» 


138  CELESTIAL  NAVIGATION 

Obs.  Alt.  =  53°  52'  40" 
I.  E.=         +2' 43" 


53°  55'  23" 

Dip=         -4' 36" 

53°  50'  47" 

Refraction  =         -0   42" 

True  Alt.  or  a=   53°  50'    5" 

P=   73°  24'  55" 

cosec  = 

.01845 

/=    15°  14'    0" 

sec  = 

.01553 

2)142°  29'    0" 

5=    71°  14'  30" 

cos  = 

9.50729 

S-a=    17°  24'  25" 

sin  = 

9.47593 

2)19.01720 
sin  i  H.  A.=   9.50860 
*H.  A.  =  2b  30"'  32=  E  (Column  p.  m.) 
*R.  A.  =  6h  40'"55« 
L.  Sid.  T.  Oct.  18  =  4"  10"' 23» 
G.  Sid.  T.  Oct.  18  =  Oh  48°'    2^ 
Diflf.  =  3h  22'"  2P 
Long.  =  50°  35'  15"  E.     Ans. 
Equal  Altitudes  Near  Noon. — Observe  an  altitude  of  the 
sun  shortly  before  noon  (usually  as  many  minutes  as  there 
are  degrees  in  the  latitude  in),  clamp  the  sextant,  and  note 
carefully  the  reading  of  the  chronometer  at  instant  of  observ- 
ing.    After  the  sun  has  crossed  the  meridian  and  begins  to 
descend,  watch  by  means  of  the  clamped  sextant  the  moment 
when  it  attains  the  same  altitude,  and  note  the  chronometer 
at  that  instant.     Find  the  mean  of  the  two  times  by  divid- 
ing their  sum  by  2.     Correct  this  time  for  whatever  error 
the  chronometer  may  have.     The  result  will  be  the  G.  M.  T. 
at  apparent  noon.     Find,  from  the  Nautical  Almanac,  the 
equation  of  time;  correct  it  for  the  G.  M.  T.  and  apply  it  to 
the  apparent  time  at  noon  (=0''  O""  0').     The  result  will  be 
the  L.  M.  T.  at  apparent  noon.     The  difference  between  the 
local    and    Greenwich    time,    converted    into  degrees,    etc., 
will  be  the  approximate  longitude  of  the  ship  at  instant  of 
apparent  noon. 


CELESTIAL  NAVIGATION  139 

If  the  vessel  has  sailed  toward  the  sun,  in  the  interval 
between  observations,  the  second  altitude  should  be  increased 
by  resetting  the  sextant  as  many  minutes  as  there  are  miles 
in  the  difference  of  latitude;  if  the  vessel  has  sailed  from 
the  sun,  the  second  altitude  should  be  decreased  in  the 
same  proportion.  Thus,  if  the  first  altitude  is  62°  24',  and 
the  ship  in  the  interval  of  time  has  changed  her  latitude 
5'  toward  the  sun,  the  sextant,  when  taking  the  second 
observation,  should  be  set  to  62°  29';  if  she  has  sailed  from 
the  sun,  the  instrument  should  be  set  to  62°  19',  before 
measuring  the  second  altitude. 

Example. — On  Aug.  16,  1904,  in  lat.  12°  N,  the  sun  was 
observed  to  have  equal  altitudes  when  near  the  meridian 
at  the  following  times  by  the  chronometer:  Before  noon, 
4>^  10"=  25^  after  noon,  41^  30'"  23«.  Find  the  longitude  of 
the  ship,  the  error  of  the  chronometer  on  Greenwich  mean 
time  being  2°^  10'  fast. 

Solution. — Chron.  before  noon  =  4h  lO^^  25' 
Chron.  after  noon  =  4b  30""  23' 


2)81^  40°^  48' 

Mid.  time  =  411  20>"  24' 

Error  (fast)  -2'"  10' 


G.  M.  T.  at  noon  =  4''  IS"'  14' 
Eq.  of  T.  Aug.  16  =  4"  11'  Change  in  1^  =  0.5' 

Corr.=    -  2.15'  X4.3»' 

Corr.  Eq.  of  T.=4""    8.85'  (  +  )  Corr.=2.15» 

L.  App.  T.  at  noon  =  0'^    0"    0' 
Eq.  ofT.=     +4-°    8.9' 
L.  M.  T.  at  noon  =  0h    4-"    8.9' 
G.  M.  T.  at  noon  =  4'>  18"  14 


Diff.  =  4''  14°'  5.1' 
Long.  =  63°  31.3' W.  Ans. 
Sunrise  and  Sunset  Sights. — When  the  sun's  upper  or 
lower  limb  is  exactly  in  contact  with  the  sea  horizon,  either 
at  sunrise  or  sunset,  note  the  chronometer  and  correct  its 
time  for  any  error  it  may  have.  For  the  G.  D.  thus  found, 
find,   from   the    Nautical   Almanac,    the   equation  of  time, 


140  CELESTIAL  NAVIGATION 

the  declination,  and  thence  the  polar  distance.  To  the 
polar  distance,  add  the  latitude  at  observation,  and  from 
the  sum  subtract  21'  if  lower  limb  was  observed,  or  53'  if 
upper  limb  was  used.  Half  the  sum  thus  obtained  is  the 
quantity  S  in  the  formula  for  hour  angles.  By  adding  to 
5  the  21'  or  53'  previously  subtracted,  the  quantity  (S  —  a) 
is  had,  whence  the  longitude  is  computed  in  the  usual  way. 
as  shown  in  the  example  that  follows: 

Example. — On  Sept.  10,  1904,  at  sunset,  the  chronometer 
indicated  S^  37"'  26^  when  the  sun's  lower  edge,  or  limb, 
came  into  contact  with  the  horizon;  the  chronometer  s  error 
on  G.  M.  T.  was  5"  56«  fast;  lat.  in,  by  dead  reckoning,  was 
48°  10'  N.     Find  the  longitude. 

Solution.—  Chron.  =8^  S?""  26* 

Error  (fast)  =   -  5''  5& 

G.  M.  T.  Sept.    10  =  8''  31™  30" 

Eq.  of  T.  =2'"  59.68  Change  in  li>  =  0.86'' 

Corr.=      +7.38  X8.5»' 


Corr. 

Eq.  of  T.  =  S 

m 

6.9B 

Decl. 

=  N  5° 

0' 

34" 

Corr. 
Decl. 

= 

8' 

3" 

Con- 

=       4° 

52' 

31" 

P.  D. 

90° 

0' 

0" 

=    85° 

7' 

29" 

Lat. 

=     48° 

10' 

0" 

133° 

17' 

29" 

Co 

nstant 

= 

21' 

0" 

2)132° 

56' 

29" 

S 

=     66° 

28' 

15" 

Constant 

+  21' 

0" 

)  Corr.  =  7.310" 

Change  in  1^=   56.8" 

X8.5»' 

Corr.  =  482.8"  =  8' 3* 


cosec=   0.00158 
sec=   0.17590 


cos=   9.60121 
iS-a)=    66°  49' 15"  sin  =  9.96345 


2)19.74214 
sini  H.  A.=   9.87107 


CELESTIAL  NAVIGATION  141 

L.  App.  T.  =  6»'  24'°    0« 
Eq.  of  T.=     -S"*    7« 

L.  M.  T.  Sept.  10  =  6b  20'"  53'  p.  m. 
G.  M.  T.  Sept.  10  =  8''  31"  30«  p.  m. 

Diff.  =  2h  10"37« 
Long.  =  32°39.2' W.     Ans. 

The  longitude  thus  found  is  approximate  only.  It  is 
evident  that  an  abnormal  refraction  caused  by  unusual 
atmospheric  conditions  at  setting  or  rising  often  renders  this 
method  unreliable.  Its  value  lies  in  the  fact  that  the  obser- 
vation can  be  made  without  the  sextant,  and  hence,  if  that 
instrument  for  some  reason  is  rendered  useless,  the  longitude 
may  be  found  simply  by  using  a  smoked  glass  to  note  the 
contact  .of  the  sun's  limb  with  the  horizon. 


142  CELESTIAL  NAVIGATION 

SUMNER'S  METHOD 
Sumner's  method  consists  in  fixing  the  position  of  a  ship  at 
sea  by  means  of  astronomical  cross-bearings  or  by  the  inter- 
section of  lines  of  position.  A  line  of  position,  also  called  a 
Sumner  line,  is  a  line  drawn  through  a  calculated  position  at 
right  angles  to  the  observed  body.  Thus,  a  Sumner  line 
can  be  obtained  whenever  a  sight  of  the  sun  or  any  other 
celestial  body  is  taken.  For  instance,  in  the  morning,  when 
measuring  the  sun's  altitude  for  a  time  sight,  the  observer 
calculates  the  longitude,  and  uses  the  same  data  for  calcu- 
lating the  true  azimuth  (or  finds  the  azimuth  directly  from 
tables).  The  azimuth  is,  of  course,  the  sun's  true  bearing 
at  the  moment  that  the  altitude  is  measured.  He  then  plots 
the  position  on  the  chart,  and  through  the  longitude  thus 
found,  and  the  latitude  used  in  the  computation,  he  draws 
a  line  perpendicular  to  the  sun's  true  bearing  or  azimuth. 
This  line  is  his  Sumner  line;  he  is  somewhere  on  this  line, 
provided  that  his  chronometer  is  not  wrong  and  no  errors 
have  been  made  in  measuring  the  altitude  or  in  the  compu- 
tations. His  exact  position  on  that  line  will  depend  on  the 
exactness  of  the  latitude  used;  but,  whatever  the  error  in 
the  latitude,  whether  it  is  10'  or  20',  the  navigator  will 
have  the  great  satisfaction  of  knowing  that  his  vessel  is 
on  that  line.  Now,  having  one  line  established,  a  second 
line  may  be  had  by  a  similar  observation,  when  the  sun 
has  changed  its  azimuth  enough  to  insure  a  defined  point 
of  intersection  between  the  two  lines.  Since  the  position 
of  the  ship  must  be  on  each  and  both  of  these  lines,  it  is 
evident  that  its  exact  position  must  be  at  their  point  of 
intersection.  If,  therefore,  one  observation  for  time  sight 
is  made  early  in  the  morning  and  another  some  time  later, 
when  the  bearing  of  the  sun  has  changed  at  least  two  points, 
two  Sumner  lines  are  obtained  whose  point  of  intersection 
will  be  the  position  of  the  ship,  unless  the  ship  has  not  moved 
in  the  interval  between  the  observations.  But  in  case  the 
ship  has  changed  its  position  in  the  interval,  which  is  more 
likely,  the  first  Sumner  line  is  carried  forwards,  parallel 
to  itself,  according  to  the  course  and  distance  run,  when 
its  intersection   with   the  second   Sumner  line   will   be   the 


CELESTIAL  NAVIGATION  143 

position  of  the  ship  at  the  time  the  second  observation  is 
made. 

This,  in  brief,  is  the  whole  theory  of  Sumner's  method. 
The-  various  forms  of  its  utiUty  in  navigation  is  practically 
unlimited,  especially  in  approaching  or  navigating  along 
a  coast  line,  when  a  Sumner  line  in  combination  with,  for 
instance,  a  chain  of  sounding  or  a  single  bearing  of  a  distant 
light,  or  other  known  object,  will  accurately  fix  the  position 
of  a  ship.  (See  Nautical  Astronotry,  Part  4,  I.  C.  S.  Ocean 
Navigation  Course.)  It  should  be  remembered  that  a 
Sumner  line  may  be  had  from  any  kind  of  observation, 
whether  it  be  for  latitude  or  for  longitude,  provided  that 
the  true  bearing  of  the  observed  object  is  noted  at  instance 
of  measuring  the  altitude.  Thus  the  Sumner  line  result- 
ing from  a  meridian  altitude  of  the  sun  will  run  true  east 
or  west,  and  may  be  combined  with  a  second  line  obtained 
by  a  time  sight  taken  2  or  3  hr.  later,  or  2  or  3  hr.  before 
noon.  Probably  the  most  valuable  Sumner  line  obtainable 
is  that  from  a  star  or  planet  at  morning  twilight  crossed 
by  a  subsequent  line  obtained  from  the  sun;  or  one  from 
the  sun  in  the  latter  part  of  the  afternoon  crossed  by  a  sub- 
sequent line  from  a  star  or  planet  at  evening  twilight.  The 
star  or  planet  selected  should,  in  each  case,  be  situated  so 
that  the  resulting  line  will  cross  the  line  obtained  from  the 
sun  at  right  angles,  or  nearly  so,  in  order  to  establish  a  good 
point  of  intersection. 

It  is  evident  that  if  the  bearing  of  the  object  is  taken  by 
compass  in  order  to  get  the  true  bearing,  allowance  must 
be  made  for  variation  and  deviation  due  to  the  direction  of 
the  ship's  head  when  observing. 

In  connection  with  th€  plotting  of  Sumner  lines  be  careful 
not  to  soil  or  deface  the  chart.  If  a  regular  chart  is  used, 
draw  very  light  pencil  lines  and  avoid  the  common  practice 
of  using  the  dividers  in  such  manner  as  to  punch  holes  at 
every  step.  A  good  idea  is  not  to  use  the  chart  for  this 
purpose  at  all.  Simply  construct  a  chart  on  a  suitable 
sheet  of  paper  and  on  a  sufficiently  large  scale  according  to 
directions  given  on  page  105.  This  will  give  more  satisfac- 
tion and  will  save  the  regular  chart  from  being  worn  out  too 


144  CELESTIAL  NAVIGATION 

soon.  In  fact,  it  is  not  always  possible  to  plot  lines  on  a 
chart  of  small  scale,  and,  moreover,  a  navigator  may  not 
always  have  at  his  command  sufficient  table  space  to  spread 
out  a  good-sized  chart. 

Illustration. — Suppose  that  a  time  sight  of  the  sun  is  taken 
in  the  morning  and  that  the  resulting  long,  is  46°  50'  W; 
the  lat.,  by  dead  reckoning  is  somewhat  uncertain,  but  is 
assumed  to  be  50°  45  N,  and  this  value  is  therefore  used 
in  computing  the  hour  angle.  At  instance  of  observation, 
the  sun's  true  bearing  was  S  75°  E,  and  hence  the  resulting 
Sumner  line  runs  N  15°  E  and  S  15°  W.  This  line  a  h,  in 
the  appended  diagram,  is  now  laid  down  on  the  chart  through 
the  position  found  and  at  right  angles  to  the  true  bearing 
of  the  sun.  The  ship's  position  is  now  somewhere  on  this 
line,  but  on  account  of  the  uncertainty  of  the  latitude  used, 
we  cannot  tell  exactly  where  until  a  second  line  is  established. 
After  making  a  run  W  S  W  60  mi.  another  sight  is  taken, 
and  the  position  thus  found  is  in  lat.  50°  28'  N  and  long. 
48°  25'  W.  The  true  bearing  of  the  sun  at  the  second  sight 
is  S  8°  E,  and  hence  the  resulting  Sumner  line  c  d  runs 
S  82°  W  and  N  82°  E.  In  order  to  find  the  trxie  position,  we 
proceed  as  follows:  From  any  point  x  on  the  first  Sumner 
line,  lay  off  the  course  and  distance  run  in  the  interval 
between  sights,  in  this  case  W  S  W  60  mi.,  and  at  the  extrem- 
ity y  of  this  line  draw  a  h'  parallel  to  the  first  Sumner  line, 
so  that  it  will  intersect  c  d,  the  second  Sumner  line.  The 
point  z  where  a  b'  crosses  c  d  will  be  the  true  position  of 
the  ship  at  time  of  taking  the  second  sight,  its  lat.  and 
long,  being,  respectively,  50°  29'  N  and  48°  15'  W,  To  find 
the  true  position  of  the  ship  at  time  of  the  first  sight,  we 
draw  a  line  from  c,  toward  a  h  parallel  to  x  y,  the  course 
run;  the  point  o  where  this  line  intersects  a  b  was  the  position 
of  the  ship  at  first  observation.  By  inspection  of  the  chart, 
it  will  be  noticed  that  the  latitude  assumed  and  used  in  the 
first  sight  was  nearly  8  miles  in  error 


CELESTIAL  NAVIGATION 


145 


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146 


SAILIXG  DISTANCES 


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SAILING  DISTANCES 


147 


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ADDITIONAL  SAILING  DISTANCES,  IN  NAUTICAL  MILES, 

BETWEEN  THE  MOST  FREQUENTED  PORTS  OF 

THE  WORLD 


Bermudas  to  Nassau 

Boston  to  Halifax 

Boston  to  Liverpool  (via  Halifax) 

Cape  Bonavista  to  Cape  Spear 

Cape  Spear  to  Cape  Race 

Cape  Race  to  Liverpool 

Cape  Race  to  Halifax 

Cape  Race  to  Boston 

Cape  Race  to  New  York 

Cape  Race  to  Philadelphia 

Cape  Race  to  Cape  Pine 

Colon  to  St.  Thomas 

Halifax  to  Liverpool 

Honolulu  to  Apia 

Honolulu  to  Dutch  Harbor 

Honolulu  to  Hong  Kong '. .  . 

Honolulu  to  Numed 

Honolulu  to  Panama 

Honolulu  to  San  Diego 

Honolulu  to  San  Francisco 

Honolulu  to  Tahiti 

Honolulu  to  Valparaiso 

Honolulu  to  Vancouver 

Honolulu  to  Wellington 

Manila  to  Hong  Kong 

New  Orleans  to  Colon .  . 

New  Orleans  to  Havana 

New  Orleans  to  Minatitlan 

New  York  to  Barbados 

New  York  to  Colon 

New  York  to  Gibraltar 

New  York  to  Havre 

New  York  to  Bremerhaven 

New  York  to  Liverpool 

New  York  to  London 

New  York  to  Havana 

New  York  to  Panama  (via  Cape  Horn) 

New  York  to  Pernambuco 

New  York  to  San  Juan,  Porto  Rico.    . . 

New  York  to  Minatitlan 

New  York  to  St.  Thomas 

New  York  to  St.  Vincent 


•  In<lloatc§  distance  along  the  great-circle  track. 


ADDITIONAL  SAILING  DISTANCES,  IN  NAUTICAL  MILES, 
BETWEEN  THE  MOST  FREQUENTED  PORTS  OF 
THE  WORLD— {Continued) 


Panama  to  Acapulco 

Panama  to  David  Chiriqui 

Panama  to  Gulf  of  Fonseca 

Panama  to  Manzanilla 

Panama  to  Monterey 

Panama  to  Punta  Arenas 

Panama  to  San  Diego 

Panama  to  Wellington 

Quebec  to  Liverpool 

Quebec  to  Plymouth 

San  Francisco  to  Apia 

San  Francisco  to  Acapulco 

San  Francisco  to  Columbia  River  Bar 

San  Francisco  to  Dutch  Harbor 

San  Francisco  to  Honolulu 

San  Francisco  to  Humboldt 

San  Francisco  to  Manzanilla 

San  Francisco  to  Panama 

San  Francisco  to  Portland 

San  Francisco  to  Port  Townsend 

San  Francisco  to  San  Diego 

San  Francisco  to  San  Juan  del  Sud.  .  . 

San  Francisco  to  Tahiti 

San  Francisco  to  Vancouver 

San  Francisco  to  Valparaiso 

San  Francisco  to  Yokohama 

San  Francisco  to  Victoria 

St.  Johns,  N.  F.,  to  Quebec 

St.  Johns,  N.  F.,  to  Boston 

St.  Johns,  N.  F.,  to  Bristol 

St.  Johns,  N.  F.,  to  Cape  Bona  vista. . 

St.  Johns,  N.  F.,  to  Cape  Spear 

St.  Johns,  N.  F.,  to  Cape  Race 

St.  Johns,  N.  F.,  to  Galway 

St.  Johns,  N.  F.,  to  Greenock 

St.  Tohns,  N.  F.,  to  Liverpool 

St.  Johns,  N.  F.,  to  St.  Peter's  Light. 

Yokohama  to  Apia 

Yokohama  to  Honolulu 

Yokohama  to  Sydney 

Yokohama  to  Vancouver 


•  Indicates  distance  along  the  great-circle  track. 


150  UNITED  STATES  NAVY 

UNITED  STATES  NAVY 


ORGANIZATION  OF  THE  NAVY 

Administrative  Bureaus. — By  the  Constitution  of  the 
United  States,  the  President  is  Commander-in-Chief  of  the 
Navy,  but  in  practice  most  of  the  administrative  details 
are  left  to  the  Secretary  of  the  Navy,  who  is  assisted  by  an 
Assistant  Secretary  and  by  the  chiefs  of  eight  Bureaus, 
between  Which  the  work  of  the  Navy  Department  is  divided. 
These  Bureaus  are:  The  Bureau  of  Yards  and  Docks,  the 
Bureau  of  Equipment,  the  Bureau  of  Navigation,  the 
Bureau  of  Ordnance,  the  Bureau  of  Construction  and 
Repair,  the  Bureau  of  Steam  Engineering,  the  Bureau  of 
Supplies  and  Accounts,  the  Bureau  of  Medicine  and  Surgery. 

In  a  general  way,  the  above  titles  are  descriptive  of  the 
duties  of  the  Bureaus,  except  in  the  case  of  the  Bureau  of 
Navigation,  which  would  be  more  accurately  described  as 
the  Bureau  of  Personnel,  since  it  has  nothing  whatever  to 
do  with  navigation  and  has  everything  to  do  with  the 
enlistment  and  training  of  men,  the  assignment  of  officers 
and  crew  to  stations  afloat  and  ashore,  and,  broadly  speak- 
ing, with  all  matters  of  organization,  drill,  and  discipline. 

A  Chief  of  Bureau,  while  serving  in  that  capacity,  has  the 
rank  and  pay  of  a  rear-admiral,  no  matter  what  his  actual 
rank  may  be  on  the  Navy  List. 

Navy  Yards. — Each  navy  yard  is  under  the  command  of 
a  Commandant,  who  is  either  a  rear-admiral  or  a  captain; 
but  each  of  the  Navy  Department  Bureaus  has  its  repre- 
sentative in  charge  of  its  own  work  at  the  yard,  and  main- 
tains an  intimate  oversight  and  control  of  all  such  work. 

The  present  navy  yards  are  at  Portsmouth,  N.  H.;  Boston, 
Mass.;  Brooklyn,  N.  Y.;  Philadelphia,  Pa.;  Norfolk,  Va.; 
Pensacola  Fla.;  Mare  Island,  Cal.;  and  Bremerton,  Wash. 
There  are,  also,  naval  stations  at  Newport,  R.  I.;  New 
London,  Conn.;  Washington,  D.  C. ;  Port  Royal  and  Charles- 
ton, S.  C. ;  Key  West,  Fla.;  Algiers,  La.;  San  Francisco  and 
San  Diego,  Cal. 


UNITED  STATES  NAVY  151 

Training  stations  for  enlisted  men  are  maintained  at 
Newport,  R.  I.,  Norfolk,  Va.,  and  San  Francisco,  Cal.,  and 
an  appropriation  has  been  made  for  establishing  one  in  the 
Great  Lakes. 

Officers. — The  officers  of  the  Navy  are  divided  into  Line 
officers  and  Staff  officers;  the  Staff  corps  including  medical 
officers,  pay  officers,  and  chaplains,  as  sea-going  officers; 
and  naval  constructofs,  civil  engineers,  and  professors  of 
mathematics  for  service  on  shore  only. 

The  grades  in  the  Line,  with  the  grades  to  which  they 

correspond  in  the  Army,  are  as  follows: 

Admiral General 

Vice-Admiral Lieutenant -General 

T^  A  1     •     1  f  Major-General 

Rear- Admiral \  t,  ■      ■,■      r-  , 

I  Brigadier-General 

Captain Colonel 

Commander Lieutenant-Colonel 

Lieutenant-Commander Major 

Lieutenant Captain 

Lieutenant,  junior  grade First  Lieutenant 

Ensign Second  Lieutenant 

Midshipman Cadet 

Chief  Boatswain Second  Lieutenant 

Chief  Gunners Second  Lieutenant 

Chief  Carpenters  (are  staff  offi- 
cers)  Second  Lieutenant 

Chief  Sailmakers    (are  staff  offi- 
cers)   Second  Lieutenant 

The  grades  in  the  staff  corps,  with  corresponding  rank  in 
the  Line,  are  as  follows: 

Medical  Corps 

Medical  Directors With  rank  of  Captain 

Medical  Inspectors With  rank  of  Commander 

Surgeons With  rank  of  Lieutenant- 
Commander 
Passed     Assistant     Sur- 
geons   With  rank  of  Lieutenant 

Assistant  Surgeon With  rank  of  Lieutenant 

junior  grade 


152  UNITED  STATES  NAVY 

Pay  Corps 

Pay  Directors With  rank  of  Captain 

Pay  Inspectors With  rank  of  Commander 

Paymasters With  rank  of  Lieutenant- 
Commander  and  Lieutenant 
Passed  Assistant  Pay-     With  rank  of  Lieutenant, 
masters  junior  grade 

Assistant  Paymaster With  rank  of  Ensign 

Chaplain With  rank  of  Captain,  Commander, 

or  Lieutenant 
Professors     of     Mathe-  f  With  rank  of  Captain,  Commander, 

mattes   \      or  Lieutenant 

Naval  Constructors  and  f  With  rank  of  Captain,  Commander, 
Assistant  Naval  Con-<      Lieutenant,  or  Lieutenant,  junior 

structors L     grade 

Civil   Engineers   and  f  With  rank  of  Captain,  Commander, 
Assistant  Civil  Engi-<      Lieutenant,  or  Lieutenant,  junior 

neers I       grade 

The  Warrant  officers  are  the  following:  Boatswains, 
gunners,  carpenters,  sailmakers,  pharmacists,  warrant 
machinists. 

Mates  are  officers,  but  have  neither  commissions  nor 
warrants. 

The  numbers  of  Line  officers  allowed  by  law  in  the  different 
grades  are  as  follows:  Admiral,  1;  vice-admiral,  — ;  rear- 
admirals,  18;  captains,  70;  commanders,  112;  lieutenant- 
commanders,  186;  lieutenants,  324.  In  the  grades  below 
lieutenant,  the  number  is  not  at  present  limited  by  law. 

Titles  of  OflBcers. — In  conversation,  admirals  and  captains 
are  addressed  by  their  titles.  A  commander  may  be  properly 
addressed  by  his  title,  or  as  Captain.  And  any  officer  who 
is  actually  in  command  of  a  ship  is  by  courtesy  addressed 
as  captain.  All  other  Line  officers  are  addressed  as  Mister. 
Medical  officers  are  commonly  addressed  as  Doctor,  but  it  is 
not  unusual  to  address  a  medical  director,  medical  inspector, 
or  surgeon  by  his  ranking  title.  Similarly,  pay  officers  of  high 
rank  are  commonly  addressed  by  their  ranking  titles,  but  those 
below  the  actual  rank  of  paymaster  are  called  Paymaster. 


UNITED  STATES  NAVY  153 

Insignia  of  Naval  OflBcers. — The  insignia  of  the  various 
grades  are  of  two  kinds,  the  first  consisting  of  a  device  worn 
on  the  collar,  the  shoulder  strap,  or  the  epaulet;  the  second, 
of  an  arrangement  of  stripes  on  the  sleeve. 

The  device  for  the  collar  or  shoulder  consists  of  two 
parts,  one  indicating  the  branch  of  the  service  to  which 
the  wearer  belongs,  the  other,  his  rank  in  that  branch. 

Line  officers  wear  a  silver  foul  anchor. 

Medical  officers  wear  a  gold  oak  leaf  on  which  is  embroid- 
ered a  silver  acorn. 

Pay  officers  wear  a  silver  oak  sprig. 

Naval  constructors  wear  a  gold  sprig  of  two  live  oak 
leaves  and  "a  silver  acorn. 

Professors  wear  a  silver  oak  leaf  and  an  acorn. 

Civil  engineers  wear  the  letters  C.  E.  in  silver. 

Chaplains  wear  a  silver  cross. 

The  insignia  of  rank  in  the  Line  and  the  various  Staff 
corps  are  as  follows.  These  are  worn  in  connection  with 
the  preceding  Corps  marks. 

Admiral Four  silver  stars 

Rear- Admiral Two  silver  stars 

Captain A  silver  spread  eagle 

Commander A  silver  oak  leaf 

Lieutenant-Commander.. .  .A  gold  oak  leaf 

Lieutenant Two  silver  bars 

Lieutenant,  junior  grade. .  .One  silver  bar 

Ensign A  silver  foul  anchor 

Midshipman A  gold  foul  anchor 

Chief  Boatswain Two  silver  foul  anchors  crossed 

Chief  Gunners A  flaming  spherical  shell  in  silver 

Chief  Carpenter A  charm  of  silver 

Chief  Sailmaker A  diamond  in  silver 

The  rank  and  corps  are  furtHer  indicated  by  stripes  on 
the  sleeves,  as  follows: 

Admiral • Two  stripes  of  2-in.  gold  lace  with 

one  stripe  of  1-in.  lace  between 

Rear-Admiral One   stripe  of  2-in.  gold  lace  with 

one  stripe  of  ^-in.  lace  above 
Captain Four  stripes  of  ^-in.  gold  lace 


154  UNITED  STATES  NAVY 

Commander Three  .stripes  of  i-in.  gold  lace 

Lieutenant-Commander. .  .Two  stripes  of  i-in.  gold  lace  with 
one  stripe  of  J-in.  lace  between 

Lieutenant Two  stripes  of  ^-in.  gold  lace 

Lieutenant,  junior  grade.  .One  stripe  of  -J-in.  gold  lace  with 
one  stripe  of  J-in.  lace  above 

Ensign One  stripe  of  ^-in.  gold  lace 

Midshipman One  stripe  of  J-in.  gold  lace 

All  Line  officers  wear  a  gold  star  on  the  sleeve  above 
the  stripes. 

For  Staff  officers  the  stripes  are  the  same  as  for  Line 
officers  of  corresponding  grades,  except  that;  first,  staff 
officers  do  not  wear  a  star;  and,  second,  each  staff  corps  is 
distinguished  by  colored  cloth  worn  between  the  gold  stripes, 
thus,  medical  officers  wear  dark  maroon;  pay  officers,  white; 
naval  constructors,  dark  violet;  professors,  olive  green; 
civil  engineers,  light  blue.  In  the  case  of  chaplains,  the 
gold  stripes  on  the  sleeves  are  replaced  by  black. 

Chief  boatswains,  chief  gunners,  chief  carpenters,  and 
chief  sailmakers  wear  one  stripe  of  gold  lace  interrupted  at 
intervals  of  2  in.  by  a  break  of  i  in.  filled  in  with  blue  silk. 

ENLISTMENT,  CLASSIFICATION,  AND  PAY  OF  ENLISTED 
MEN  IN  THE  UNITED  STATES  NAVY 
Recruiting  Stations. — Men  are  enlisted  at  the  following 
recruiting  stations  and  receiving  ships"  United  States 
Recruiting  Station,  87  South  Street,  New  York,  N.  Y.; 
United  States  Recruiting  Station,  22  Hanover  Street,  Boston, 
Mass.;  United  States  Recruiting  Station,  1319  Market 
Street,  Philadelphia,  Pa.;  United  States  Recruiting  Station, 
207  North  Calvert  Street,  Baltimore,  Md. ;  Seamen's  Quarters, 
U.  S.  Navy  Yard,  Washington,  D.  C;  United  States  Recruit- 
ing Station,  Masonic  Temple,  Chicago,  111.;  Receiving  ship 
Wabash,  Navy  Yard,  Boston,  Mass.;  Receiving  ship  Hancock, 
Navy  Yard,  New  York,  N.  Y.;  Receiving  ship  Lancaster, 
Navy  Yard,  League  Island,  Pa.;  Receiving  ship  Franklin: 
Navy  Yard,  Norfolk,  Va. ;  Receiving  ship  Independence,  Navy 
Yard,  Mare  Island,  Cal.;  U.  S.  Navy  Yard,  Bremerton, 
Wash.;  U.  S.  Naval  Recruiting  Station,  San  Francisco,  Cal.; 


UNITED  STATES  NAVY  155 

U.  S.  Navy  Yard,  Pensacola,  Fla.;  U.  S.  Navy  Yard,  Ports- 
mouth, N.  H.;  U.  S.  Naval  Station,  Port  Royal,  S.  C;  U.  *S. 
Naval  Recruiting  Station,  Prudential  Building,  Buffalo, 
N.  Y.;  also  at  any  traveling  recruiting  station,  information 
regarding  which  will  be  furnished  on  application  to  the 
Bureau  of  Navigation,  Navy  Department,  Washington,  D.  C. 

Applicants  for  enlistment  in  the  United  States  Navy  must 
be  over  18  years  of  age,  of  American  citizenship  and  capable 
of  reading  and  writing  English.  The  term  of  enlistment  is 
4  years,  but  no  person  will  be  accepted  until  he  has  passed 
the  medical  examination  prescribed  by  the  regulations. 

No  minor  under  the  age  of  18  years  will  be  accepted  with- 
out the  consent  of  parent  or  guardian,  and  any  such  minor 
claiming  to  be  more  than  18  years  of  age,  in  order  to  secure 
enlistment,  is  liable  to  punishment. 

Caution. — Applicants  residing  at.  a  distance  should,  in 
all  cases,  communicate  with  the  nearest  recruiting  station 
for  a  list  of  qualifications  before  reporting  for  examination, 
and  on  receipt  of  same  should  consult  a  physician  and 
ascertain  the  probabilities  of  their  being  able  to  conform 
to  the  requirements.  If  favorably  advised,  the  recruiting 
office  should  be  immediately  informed,  and  request  made 
that  the  applicant's  name  be  entered  on  the  list  to  be  noti- 
fied, after  which  complete  instructions  will  be  given  as  t6 
the  proper  time  to  report  for  examination.  This  course  is 
suggested,  as  no  allowance  is  made  for  traveling  expenses 
of  applicants,  and  they  should  be  as  certain  as  possible  of 
their  ability  to  pass  the  examination  before  incurring  any 
expense. 

Transportation  is  furnished  only  to  accepted  applicants 
from  the  recruiting  station  to  the  point  of  assignment. 

Age  Limits. — First  enlistment  may  be  made  in  the  follow- 
ing ratings  of  men  within  the  limits  of  age  indicated  in 
Table  following. 


156 


UNITED  STATES  NAVY 


Rating 


Seamen 

Ordinary  seamen 

Landsmen 

Shipwrights 

Blacksmiths 

Plumbers  and  fitters 

Machinists,  first  class 

Machinists,  second  class 

Sailmakers'  mates 

Electricians,  third  class 

Boilermakers 

Coppersmiths 

Firemen,  first  class 

Firemen,  second  class 

Landsmen,  for  yeomen 

Coal  passers 

Hospital  stewards 

Hospital  apprentices,  first  class 

Hospital  apprentices 

Officers'  stewards 

Officers'  cooks 

Mess  attendants 

Ships'  cooks,  fourth  class 

Musicians,  first  class 

Musicians,  second  class 

Buglers 

Painters 

Bakers,  second  class 

Shipfitters,  first  class 

Shipfitters,  second  class 


Years 

of  Age 

21  to  35 

18  to  30 

18  to  25 

21  to  35 

21  to  35 

21  to  35 

21  to  35 

21  to  35 

21  to  35 

21  to  35 

21  to  35 

21  to  35 

21  to  35 

21  to  35 

18  to  25 

21  to  35 

21  to  30 

21  to  28 

18  to  25 

21  to  35 

21  to  35 

18  to  30 

18  to  30 

21  to  35 

21  to  35 

21  to  35 

21  to  35 

21  to  35 

21  to  35 

21  to  35 

Ratings  and   Monthly   Pay. — In   the  following  table   are 
given  the  monthly  pay  for  the  various  ratings  in  the  Navy: 

SEAMEN  BRANCH 

Chief  Petty  Officers: 

Chief  masters  at  arms $65 

Chief  boatswains'  mates 50 

Chief  gunners'  mates 50 

Chief  gun  captains 50 

Chief  turret  captains 60 

Chief  quartermasters 50 

Petty  Officers,  First  Class: 

Masters  at  arms,  first  class $40 

Boatswains'  mates,  first  class 40 

Gunners'  mates,  first  class ; 40 


UNITED  STATES  NAVY  157 

Gun  captains,  first  class $40 

Turret  captains,  first  class 50 

Quartermasters,  first  class 40 

Petty  Officers,  Second  Class: 

Masters  at  arms,  second  class $35 

Boatswains'  mates,  second  class 35 

Gunners'  mates,  second  class 35 

Gun  captains,  second  class 35 

Quartermasters,  second  class 35 

Petty  Officers,  Third  Class: 

Masters  at  arms,  third  class $30 

Coxswains 30 

Gunners'  mates,  third  class 30 

Quartermasters,  third  class 30 

Seamen,  First  Class: 

Seamen  gunners       $26 

Seamen 24 

Apprentices,  first  class 21 

Seamen,  Second  Class: 

Ordinary  seamen $19 

Apprentices,  second  class 15 

Seamen,  Third  Class: 

Landsmen $16 

Apprentices,  third  class 9 

ARTIFICER  BRANCH 

Chief  Petty  Officers: 

Chief  machinists $70 

Chief  electricians 60 

Chief  carpenters'  mates 50 

Chief  water  tenders 50 

Petty  Officers,  First  Class: 

Boilermakers $65 

Machinists,  first  class 55 

Coppersmiths 55 

Shipfitters,  first  class 55 

Electricians,  first  class 50 

Blacksmiths 50 

Plumbers  and  fitters 45 

Sailmakers'  mates 40 

Carpenters'  mates,  first  class 40 

Water  tenders 40 

Painters,  first  class 40 

Petty  Officers,  Second  Class: 

Machinists,  second  class $40 

Electricians,  second  class 40 

Shipfitters,  second  class 40 

Oilers 37 

Carpenter's  mates,  second  class 35 

Printers 35 

Painters,  second  class 35 


15S  UNITED  STATES  NAVY 

Petty  Officers.  Third  Class: 

Electricians,  third  class : $30 

Carpenters'  mates,  third  class 30 

Painters,  third  class 30 

Seamen,  First  Class: 

Firemen,  first  class S3o 

Seamen,  Second  Class: 

Firemen,  second  class $30 

Shipwrights / 25 

Seamen,  Third  Class: 

Coal  passers $22 

SPECIAL  BRANCH 

Chief  Petty  Officers: 

Chief  commissary  steward $70 

Chief  yeoman 60 

Hospital  stewards 60 

Bandmasters 52 

Commissary  steward 60 

Petty  Officers,  First  Class: 

Yeoman,  first  class $40 

First  musicians 36 

Petty  Officers,  Second  Class: 

Yeoman,  second  class $35 

Petty  Officers,  Third  Class: 

Yeomen,  third  class $30 

Hospital  apprentices,  first  class 30 

Seamen,  First  Class: 

Musicians   first  class $32 

Seamen,  Second  Class: 

Musicians,  second  class $30 

Buglers 30 

Hospital  apprentices 20 

MESSMEN  BRANCH 

Stewards  to  commanders  in  chief $60 

Cooks  to  commanders  in  chief 50 

Stewards  to  commandants 60 

Cooks  to  commandants 50 

Cabin  stewards 50 

Cabin  cooks 45 

Wardroom  stewards 50 

Wardroom  cooks 45 

Steerage  stewards 35 

Steerage  cooks 30 

Warrant  officers'  stewards 35 

Warrant  ofl^cers'  cooks 30 

Ship's  cooks,  first  class 55 

Ship's  cooks,  second  class 40 

Ship's  cooks,  third  class 30 

Ship's  cooks,  fourth  class 25 


UNITED  STATES  NAVY  159 

Bakers,  first  class %Ab 

Bakers,  second  class 35 

Mess  attendants,  first  class 24 

Mess  attendants,  second  class 20 

Mess  attendants,  third  class 16 

Special  Pay  and  Privileges. — Every  enlisted  man  and 
apprentice  who  has  been  rated  a  seaman  gunner,  or  holds 
a  gun  captain's  certificate,  or  a  certificate  of  graduation 
from  one  or  more  classes  of  the  Petty  Officers'  School  of 
Instruction,  receives  S2  a  mo.  in  addition  to  the  pay  of 
his  rating  for  each  such  certificate. 

Each  enlisted  man  of  the  Xavy  receives  75  ct.  per  mo.  in 
addition  to  the  pay  of  his  rating  for  each  rating,  for  each 
good-conduct  medal,  pin,  or  bar  which  he  may  be  awarded. 

Coxswains  detailed  as  coxwains  of  boats  propelled  by 
machinery,  or  as  coxswains  to  commanders  in  chief,  receive 
$5  per  mo.  in  addition  to  their  pay. 

All  enlisted  men  of  the  Navy  receive  $5  per  mo.  in 
addition  to  their  pay  while  serving  on  board  of  submarine 
vessels  of  the  Navy. 

Seamen  in  charge  of  holds  receive  S5  per  mo.  in 
addition  to  their  pay. 

Landsmen  assigned  to  duty  as  jacks-of-the-dust,  or  as 
lamplighters,  receive  $5  per  mo.  in  addition  to  their  pay. 

Enlisted  men  detailed  as  crew  messmen  while  so  acting, 
except  when  assigned  as  reliefs  during  the  temporary 
absence  of  the  regular  crew  messmen,  receive  extra  com- 
pensation at  the  rate  of  So  per  mo. 

Enlisted  men  of  the  naval  ser\ace  regularly  detailed  as 
signalmen  receive  the  following  extra  compensation  in 
addition  to  the  monthly  pay  of  their  rating:  Signalmen, 
first  class,  $3;  signalmen,  second  class,  $2;  signalmen,  third 
class,  $1. 

All  enlisted  men  of  the  navy,  after  having  qualified  as 
gun  pointers,  and  who  are  regularly  detailed  as  gun 
pointers  by  the  commanding  officer  of  the  vessel,  receive 
monthly,  in  addition  to  the  pay  of  their  respective  ratings, 
extra  pay  as  follows:  Heavy  gun  pointers  of  the  first  class, 
SlO:  heavy  gun  pointers  of  the  second  class  $6;  inter- 
mediate  gun   pointers   of     the    first  class,  $8;  intermediate 


160  UNITED  STATES  NAVY 

gun  pointers  of  the  second  class,  $4;  secondary  gun  pointers 
of  the  first  class,  $4;  secondary  gun  pointers  of  the  second 
class,  $2. 

Enlisted  men  of  the  Navy  regularly  detailed  by  the  com- 
manding officer  of  a  vessel  as  gun  captains,  except  of  second- 
ary batlery  guns,  receive,  in  addition  to  the  pay  of  their 
respective  ratings,  $5  per  mo.,  which  in  the  case  of  men  hold- 
ing certificates  as  gun  captains,  or  of  graduation  from  the 
gun  captain  class.  Petty  Officers'  School,  shall  include  the  $2 
per  mo.  to  which  such  certificate  entitles  them. 

Additional  Rewards. — The  pay  of  the  various  grades  may 
not  seem  large,  but  it  must  be  remembered  that  it  is  nearly 
all  clear.  The  ship  constitutes  a  comfortable  home  and  the 
government  supplies  an  excellent  ration.  An  outfit  of  cloth- 
ing is  issued  free  at  the  beginning  of  an  enlistment. 
Medical  and  hospital  attendance  are  free.  Thus,  the  only 
real  demand  on  the  pay  is  for  keeping  up  the  outfit  of 
clothing.  Men  can  and  do  save  very  large  sums  of  money, 
and  these  sums  they  have  the  privilege  of  depositing  with 
the  government,  which  allows  interest  at  the  rate  of  4% 
compounded.  There  are,  moreover,  many  additions  to  the 
pay  for  special  details  of  duty  and  special  excellencies  of 
various  kinds.  A  man  distinguished  in  marksmanship  and 
serving  as  pointer  of  a  turret  gun  receives  $10  per  mo.  in 
.addition  to  his  regular  pay.  An  expert  signalman  gets  $5 
additional;  and  so  with  many  other  cases,  as  indicated  in  the 
pages  that  follow. 

A  man  having  served  one  term  of  enlistment  and  having 
been  honorably  discharged,  if  he  reenlists  within  4  mo., 
receives  a  bonus  of  4  mo.  pay.  This  amounts  in  the  higher 
ratings  to  as  much  as  $280.  Moreover,  for  each  reenlistment 
his  monthly  pay  is  slightly  increased. 

In  case  of  disability  from  illness  or  accident,  not  only  is 
a  man  fully  cared  for  without  charge  but  his  full  pay  goes 
on,  no  matter  how  long  the  disability  may  continue;  and 
in  the  case  of  permanent  disability  resulting  from  causes 
incident  to  the  service,  he  receives  a  pension  for  life,  pro- 
vided that  lie  has  served  10  yr.  Even  though  he  may  be 
in  perfect  health,  lie  has  the  privilege    on  reaching  50  yr. 


UNITED  STATES  NAVY  161 

of  age,  provided  that  he  has  served  for  30  yr.,  of  being 
placed  on.  the  retired  list  for  the  remainder  of  his  life  with 
three-quarters  of  the  full  pay  of  his  grade.  If  he  is  a  chief 
petty  officer,  and  any  reasonably  deserving  man  would 
surely  be  this  after  30  yr.  service,  this  retired  pay  is  $52.50 
per  mo.,  and  for  this  he  is  not  called  upon  to  make  any 
return  whatever. 

Although,  in  general,  a  man  must  expect  in  the  Navy,  as 
elsewhere,  to  begin  at  the  bottom  and  work  his  way  up, 
there  are  many  well-paid  positions  for  which  competent  men 
are  enlisted  directly.  Thus,  a  man  who  is  already  a  com- 
petent seaman  is  gladly  taken  in  as  such,  and,  owing  to 
the  great  demand  for  coxswains,  quartermasters,  etc.,  he 
may  reasonably  expect  almost  immediate  advancement  to 
one  of  these  ratings.  So,  in  the  artificer  branch,  a  man  who 
is  qualified  for  machinist,  water  tender,  fireman,  boilermaker, 
electrician,  plumber,  painter,  etc.  is  enlisted  directly  as  such. 

Naval  Apprentices. — Boys  between  the  age  of  17  and  18  yr. 
may,  with  the  consent  of  their  parents  or  guardians,  be 
enlisted  to  serve  as  apprentices  in  the  Navy  until  they 
reach  the  age  of  21  yr.  They  are  trained  to  fill  the  positions 
of  seamen,  petty  officers,  and  warrant  officers,  and  from 
these  positions  they  can  be  advanced  to  be  commissioned 
officers  in  the  Navy.  Their  pay  as  apprentices  begins  at 
$9  per  mo    and  increases  to  $21. 

BRIEF  OUTLINE  OF  DUTIES 
Master  at  Arms. — The  chief  master  at  arms  is  the  chief  of 
police  of  the  ship.  He  has  from  one  to  three  or  four  assist- 
ants, according  to  the  size  of  the  ship.  It  is  the  duty  of 
these  men  to  suppress  disorder,  to  arrest  offenders  where 
physical  restraint  is  needed,  and  to  confine  any  one  .if  ordered 
to  do  so  by  proper  authority.  They  have  charge  of  the 
cleanliness  of  the  ship  on  the  lower  decks  and  are  responsible 
for  the  eating  arrangements  of  the  men,  so  far  as  regards 
the  condition  of  the  tables  and  the  table  service.  The 
actual  preparation  of  the  food  is  in  charge  of  the  ship's 
cooks,  under  the  supervision  of  the  commissary  steward; 
but  the   food  is   served  by   the   berth-deck  cooks,  or  crew 


162  UNITED  STATES  NAVY 

messmen,  and  these  messmen  are  subject  to  the  direction 
of  the  master  at  arms. 

Boatswain's  Mates. — The  boatswain's  mates  are  the 
assistants  to  the  officer  of  the  deck  in  carrying  on  the  work 
of  the  ship.  All  orders  given  are  repeated  by  them,  and 
they  are  expected  to  make  sure,  not  only  that  the  orders 
are  heard  in  all  parts  of  the  ship,  but  that  they  are  obeyed. 
If  a  boat  is  to  be  hoisted,  they  "pass  the  word"  and  then 
make  sure  that  the  boat  is  properly  hooked  on,  that  the 
deck  force  "man  the  falls,"  and  that  the  boat  is  safely 
hoisted  and  secured.  They  bear  much  the  same  relation 
to  affairs  on  the  upper  deck  that  the  masters  at  arms  bear 
to  those  on  the  lower  decks,  except  that,  while  they  are 
expected  to  maintain  order,  they  have  none  of  the  police 
functions  that  belong  to  the  masters  at  arms.  They  call 
attention  by  blowing  a  silver  whistle,  or  boatswain's  call. 

Coxswains. — Coxswains  have  charge  of  boats,  their  outfits 
and  their  crews.  When  a  boat  is  absent  from  the  ship 
without  an  officer,  the  authority  of  the  coxswain  is  absolute. 

Machinists. — Machinists,  when  on  duty,  have  charge  of 
the  engine  room  and  fire-room,  have  full  authority  there 
and  full  responsibility  for  work  and  discipline.  Thus,  the 
masters  at  arms,  boatswain's  mates,  coxswains,  and  machin- 
ists are  directly  charged  with  responsibility  for  the  main- 
tenance of  discipline,  and  their  orders  are  entitled  to  the 
same  weight  as  those  of  commissioned  officers.  Other 
petty  officers  have  no  such  general  authority  as  this,  though 
many  of  them  may  be  placed  in  positions  of  authority  by 
reason  of  special  detail.  An  oiler  or  a  fireman,  for  example, 
may  do  a  machinist's  duty  in  the  engine  room;  a  gunner's 
mate  may  be  sent  in  charge  of  a  party  to  bring  off  ammu- 
nition, etc. 

Quartermasters. — The  quartermasters  have  charge  of  the 
steering  of  the  ship  and  everything  connected  with  it,  of 
the  making  and  reading  of  signals,  and  of  the  hourly  record 
of  weather,  etc.  as  entered  in  the  ship's  log.  In  port,  they 
stand  watch  on  the  bridge  and  are  responsible  for  the 
"lookout,"  reporting  to  the  officer  of  the  deck  everything 
of  importance  that  goes  on  within  sight  of  the  ship. 


UNITED  STATES  NAVY  163 

Yeomen. — Yeomen  are  writers  or  accountants;  their 
duties  are  purely  clerical.  One  yeoman  is  usually  allowed 
for  the  commanding  officers,  two  for  the  executive  officer, 
one  for  the  engineer's  department,  one  for  the  navigator, 
and  two  or  more  for  the  pay  department. 

Commissary  Steward. — The  commissary  steward  has 
charge  of  the  purchase  and  preparation  of  provisions  for 
the  men's  messes. 

The  duties  of  other  petty  officers  and  rated  men  are 
indicated  with  sufficient  exactness  by  their  titles. 

PROMOTION  OF  ENLISTED  MEN  TO  OFFICERS 

Mates. — These  are  officers,  although  not  commissioned, 
their  salary  being  S900  a  yr. 

"As  a  reward  for  long  and  faithful  service  in  the  navy, 
the  Department  will  in  the  future  appoint  ten  mates  annually 
from  the  enlisted  men  of  the  service,  appointments  to  be 
made  on  or  about  July  1  of  each  year.  No  man  will  be 
appointed  who  is  not  recommended  for  appointment  by  his 
commanding  officer  and  who  does  not  come  within  the 
following  provisions:  He  must  be  a  chief  petty  officer  of 
the  seaman  branch,  at  least  35  yr.  of  age,  serving  under 
continuous  service,  who  ^as  had  15  yr.  service  in  a  sea- 
going ship,  with  an  average  of  85%  taken  from  all  his 
enlistment  records,  and  there  must  be  on  file  in  the  Bureau 
of  Navigation  letters  of  recommendation  from  his  command- 
ing officers." 

Warrant  Officers. — Warrant  officers  rank  next  below 
commissioned  officers  in  the  service;  they  are  officers  in 
every  sense  of  the  word.  Enlisted  men  who  serve  contin- 
uously and  reach  the  grade  of  chief  petty  officer  or  first- 
class  petty  officer  are  eligible  for  appointment  as  warrant 
officers.  The  warrant  officers  are  boatswains,  gunners, 
carpenters,  sailmakers,  warrant  machinists,  and  pharma- 
cists. The  pay  of  a  warrant  officer  is  from  $1,200  to  $1,800 
a  yr.,  and  he  may  retire  at  62  yr.  of  age  on  three-quarter  pay. 

Commissioned  Officers. — Warrant  officers  after  10  yr. 
service  are  given  a  commission  and  rank  with  ensigns  of 
the    Line.     A  warrant  officer  who   can   pass   the   requisite 


164  UNITED  STATES  NAVY      " 

examination  may  be  regularly  commissioned  as  an  ensign 
in  the  Line  of  the  Navy  and  advance  through  all  the  grades 
of  the  service  up  to  admiral,  exactly  as  if  he  had  graduated 
at  the  Naval  Academy.  A  number  of  such  appointments 
have  already  been  made,  the  majority  of  appointees  being 
I.  C.  S.  nautical  students. 

Educational  Facilities  in  the  Navy. — The  earnestness  with 
which  the  Navy  endeavors  to  help  those  who  wish  to  fit 
themselves  for  advancement  in  the  service  is  evidenced  by 
the  following  statement  of  facilities  provided  for  the  purpose : 

Elaborately  equipped  training  stations  for  apprentices  are 
maintained  at  Newport.  R.  I.,  and  San  Francisco,  Cal.,  where 
from  1,000  to  2,000  young  men  are  kept  under  instruction. 

Similar  stations  for  the  training  of  recruits  other  than 
apprentices  are  maintained  at  Brooklyn,  N.  Y.,  and  at 
Norfolk.  Va.,  and  a  third  will  shortly  be  established  at  some 
point  on  the  Great  Lakes. 

Nine  large  and  comfortable  vessels  are  kept  in  cruising 
commission  for  the  training  afloat  of  recruits  of  all  branches. 
The  cruises  of  these  ships  are  varied  as  much  as  possible  with 
a  view  to  making  the  duty  interesting  as  well  as  instructive. 

The  following  special  schools  of  instruction  are  maintained, 
and  any  man  whose  abilities  and  conduct  justify  the  privilege 
can  take  a  course  in  one  or  more  of  them :  A  school  for  the 
training  of  petty  officers,  at  Newport;  a  school  for  the  train- 
ing of  torpedo  specialists,  at  Newport;  a  school  for  the  train- 
ing of  electricians,  at  Brooklyn;  a  school  for  the  training  of 
wireless  telegraphers,  at  Brooklyn;  a  school  for  the  training 
of  yeomen,  at  Brooklyn;  a  school  for  the  training  of  gunners, 
at  Washington;  a  school  for  the  training  of  gunners,  at  New- 
port; a  school  for  the  training  of  cooks,  at  Brooklyn. 

It  should  be  explained  that  the  cooks  for  whom  the 
cooking  school  exists  are  those  who  cook  for  the  enlisted 
men,  not  for  the  officers.  The  attention  that  is  given  to 
the  question  of  food  for  the  men  is  further  illustrated  by 
the  fact  that  a  board  of  oflficers  recently  spent  several 
months  in  studying  the  most  desirable  articles  to  be  pro- 
vided for  the  rations  of  the  men,  and  that  the  recommenda- 
»i,.n^  ,.f  these  officers  have  resulted  in  the  adoption  on  board 


THE  ORGANIZA  TION  OF  A  MAN  OF  WAR      165 

United  States  men  of  war  of  what  is  unquestionably  the  most 
liberal  and  most  appetizing  ration  allowed  by  any  military  or 
naval  service  in  the  world.  On  the  large  ships  of  the  Navy, 
cold-storage  rooms  are  fitted  which  admit  of  carrying  consid- 
erable quantities  of  fresh  meat  and  vegetables  and  of  furnish- 
ing cool  drinking  water  in  the  tropics.  Moreover,  the  Navy 
Department  has,  within  the  last  few  years,  adopted  the  policy 
of  keeping  refrigerating  ships  in  company  with  all  large 
squadrons  serving  on  tropical  waters,  and  these  ships  carry 
abundant  supplies  of  fresh  meats  and  vegetables,  which  are 
distributed  daily  to  all  ships  within  reach. 


THE  ORGANIZATION  OF  A  MAN  OF  WAR 

OFFICERS  AND  THEIR  DUTIES 

The  commanding  oflficer,  whatever  his  actual  rank  and 
title  on  the  Navy  List,  is  the  captain  of  the  ship,  and  as  such 
is  responsible  for  her  safety,  discipline,  and  efficiency.  He  is 
assisted  by  a  number  of  subordinate  officers,  each  of  whom 
is  charged  with  special  duties,  but  this  does  not  lessen  his 
responsibility,  which  extends  to  every  detail  throughout  the 
ship.  Even  when  a  pilot  is  taken  for  entering  and  leaving 
port,  the  captain  cannot,  as  in  the  case  of  a  merchant  vessel, 
relinquish  his  responsibility  for  the  navigation  of  the  ship, 
but  must  regard  the  pilot  as  merely  an  adviser. 

The  discipline  of  the  ship  is,  subject  to  the  captain,  in 
the  hands  of  a  certain  number  of  Line  officers,  associated 
with  whom  are  the  Staff  officers  of  various  corps;  the  medical 
officers  in  charge  of  the  health,  hygiene,  and  sanitation  of 
the  ship;  the  pay  officer,  in  charge  of  accounts,  money, 
stores,  and  purchases;  and,  on  large  ships,  chaplains. 

The  line  officer  ne.xt  in  rank  to  the  captain  is  the 
executive,  who  may  be  a  lieutenant-com.mander,  a  lieutenant, 
or  on  a  small  ship  even  an  ensign.  He  attends  to  the  details 
of  all  matters  of  organization  and  discipline,  directs  the  drills, 
keeps  the  ship  in  good  condition,  transmits  the  orders  of  the 
captain,  and  sees  that  they  are  executed — hence  his  title. 

In  immediate  charge  of  the  ship  at  any  given  time,  and 
responsible  for  the  execution  of  the  orders  of  the  captain 


1 66        THE  ORG  AX  IZ  A  TION  OF  A  MAN  OF  \V  A  R 

and  executive,  is  the  officer  of  the  deck.  There  are  usually 
three  or  four  officers  who  take  this  duty  in  turn,  "standirig 
watch,"  as  it  is  called,  for  4  hr.  at  a  time.  As  these  officers 
also  have  charge  of  the  divisions  into  which  the  crew  is 
divided  for  drills  and  for  battle,  they  are  called  watch  and 
division  officers.  At  sea,  the  officer  of  the  deck  is  always  on 
the  bridge  to  see  that  the  proper  course  is  steered,  to  look  out 
for  and  avoid  dangers,  and  to  carry  on  the  routine  of  work. 
In  port,  he  is  on  the  alert  to  maintain  order,  supervise  all 
work  that  may  be  in  progress,  receive  visiting  officials,  etc. 
In  his  capacity  as  division  officer,  he  has  command  of  a  divi- 
sion of  men  to  whom  he  stands  in  the  relation  of  the  captain 
of  a  company  in  a  military  organization.  The  watch  and 
division  officers  are  always  Line  officers,  usually  lieutenants 
or  ensigns.  They  are  assisted  in  all  of  their  duties  by  such 
junior  officers  as  may  be  assigned  to  the  ships. 

The  navigator  is  usually  the  Line  officer  next  in  rank  to  the 
executive.  He  assists  the  captain  in  the  navigation,  deter- 
mines the  position  of  the  ship  as  often  as  may  be  necessary, 
and  has  charge  of  all  the  instruments  used  for  this  purpi  ise. 

The  engineer  officers  were  formerly  a  corps  of  specialists, 
but  the  Personnel  Bill  of  1899  merged  them  in  the  Line, 
and  under  the  present  system  a  certain  number  of  Line 
officers  are  detailed  for  duty  in  charge  of  the  engineering 
department  of  the  ship,  the  actual  standing  of  watches  in 
charge  of  the  engines  and  boilers  being  entrusted  to  machinists. 

ORGANIZATION  OF  THE  CREW 
The  crew  of  a  ship  is  first  of  all  divided  into  two  parts, 
V  r  watches,  the  starboard  and  the  port.  Each  watch  is 
subdivided  into  two  parts,  the  first  and  the  second.  Thus, 
a  man's  position  on  board  is  fixed  in  one  way  by  the  state- 
ment that  he  belongs  to  the  first  part  of  the  starboard 
watch,  to  the  second  part  of  the  port  watch,  etc. 

A  more  important  assignment  is  that  to  a  division,  as 
this  not  only  fixes  his  station  in  battle,  but  indicates  the 
j>art  of  the  ship  that  he  assists  to  keep  in  order,  and  in 
which  his  most  important  duties  are  localized.  The  arrange- 
ment of  divisions  is  determined  largely  by  the  arrangement 


THE  ORGAXIZA  TION  OF  A  MAN  OF  WAR       167 

of  the  battery.  The  first  division,  for  example,  is  usually 
composed  of  the  men  stationed  at  the  guns  on  or  near  the 
forecastle;  or,  in  a  turret  ship,  of  those  stationed  in  the  for- 
ward turret.  The  ship  is  divided  into  parts  corresponding 
with  the  guns,  so  that  each  division  keeps  that  part  of  the 
ship  in  the  order  in  which  its  guns  are  situated. 

In  addition  to  the  gun  divisions  which  are  designated  by 
numbers,  there  is  the  powder  division  which  supplies  ammuni- 
tion, passing  it  from  the  magazines  to  the  guns.  This  is 
usually  the  largest  division  in  the  ship,  and  is  made  up 
chiefly  of  men  whose  regular  duties  keep  them  below  decks, 
such  as  cooks,  stewards,  mess-attendants,  waiters,  etc.  With 
these  men,  however,  are  associated  many  of  the  leading  men 
of  the  ship:  gunners,  mates,  masters-at-arms,  etc.,  charged 
with  the  safety  of  the  magazines  and  with  an  oversight  of 
the  rapid  and  uninterrupted  supply  of  ammunition. 

The  engineers'  force  constitutes  a  division  by  itself,  but 
sends  a  detail  of  firemen  and  coal  passers  to  assist  the 
powder  division  in  action. 

In  addition  to  his  station  for  routine  ship's  work  and 
for  battle,  every  man  of  the  deck  force  is  assigned  to  a 
boat  in  which  he  takes  his  place  when  that  particular  boat 
is  engaged  either  in  the  ordinary  boating  that  is  incident 
to  necessary  communication  with  other  ships  and  with 
the  shore,  or  in  the  cases  where  the  boats  take  part  in  opera- 
tions against  an  enemy.  Every  officer  and  man  on  the 
ship,  moreover,  has  his  station  in  a  boat  for  abandoning 
ship,  in  the  event  of  collision  or  wreck. 

In  every  ship,  there  is  an  organization  of  the  crew  as  a 
military  force  of  infantry  and  field  artillery  for  operations 
on  shore  in  case  the  occasion  arises  for  landing  such  a  force. 
Hardly  a  year  passes  without  the  necessity  for  operations 
of  this  kind  in  some  part  of  the  world. 

Drilling. — Each  dixnsion  on  the  ship  has  its  specified  duties 
in  the  case  of  fire,  and  -each  man  in  the  division  knows  his 
station,  whether  this  be  to  lead  out  a  hose,  to  flood  a  maga- 
zine with  water,  to  close  certain  water-tight  doors  so  that  the 
fire  shall  not  spread,  or  to  close  air  ports  or  hatches  to  prevent 
a  draft  from  fanning  the  flames;  and  all  these  duties  become 


1 68      THE  ORGANIZA  TION  OF  A  MAN  OF  WAR 

so  familiar  by  frequent  drills  that  an  actual  fire  on  board 
a  man  of  war  is  rarely  accompanied  by  any  indication  of 
excitement,  even  though  it  may  be  near  the  magazine. 
Similarly  in  case  of  collision;  every  man  knows  his  station, 
whether  it  be  to  get  the  collision  mat  over  the  side  in  hope 
of  stopping  a  leak,  to  close  the  water-tight  doors,  to  start 
the  wrecking  pump,  or  only  to  fall  in  ranks  with  his  divi- 
sion and  keep  silence  while  awaiting  instructions.  Natur- 
ally, the  most  important  drill  of  all  is  the  battle  drill,  or,  as 
it  is  called,  general  quarters;  and  when  the  call  for  this  is 
sounded,  whether  at  the  regular  morning  hour  for  drill  or 
unexpectedly  in  the  middle  of  the  night,  every  man  makes 
his  way  quickly  and  silently  to  his  station,  the  magazines 
are  opened  and  ammunition  rushed  to  the  guns;  the  guns 
are  loaded  and  swung  until  they  bear  upon  the  enemy, 
either  real  or  imaginary;  the  torpedoes  are  adjusted  and 
the  tubes  trained;  switches  are  thrown  on  for  searchlights 
and  signals;  and,  often  within  a  minute,  the  ship  is  trans- 
formed from  tranquility  and  apparent  inertness  into  a 
state  of  alert  and  vigorous  aggressiveness. 

Constant  drilling  is  carried  on  with  devices  for  training 
the  gun's  crews  in  loading,  pointing,  and  firing  the  guns. 
These  drills  have  resulted,  within  a  few  years,  in  an  extra- 
ordinary increase  in  rapidity  and  accuracy  of  fire.  Other 
drills  have  for  their  object  to  familiarize  the  men  with  the 
use  of  rifles,  revolvers,  broadswords,  etc.;  and  others  still 
aim  largely  at  physical  development,  being  in  the  nature 
of  gymnastics.  With  the  same  end  in  view,  coupled  with 
the  further  thought  of  affording  recreation,  athletic  sports 
are  encouraged,  and  outfits  for  boxing,  baseball,  and  foot- 
ball are  supplied  by  the  government  to  all  ships,  and  com- 
manding officers  are  directed  to  afford  all  reasonable  facilities 
for  the  use  of  these  and  for  competition  between  different 
ships.  All  large  ships  have  their  athletic  teams,  many  of 
them  with  records  of  which  they  have  a  right  to  be  proud. 
Most  ships  also  have  racing  boat  crews;  and  races,  both 
rowing  and  sailing,  are  frequent  when  ships  are  in  company. 

The  stations  of  the  crew  for  all  the  drills  that  have  been 
outlined  above  are  laid  down  in  a  book  known  as  the  Watch 


THE  ORGANIZA  TION  OF  A  MAN  OF  WAR      169 

Quarter  and  Station  Book,  which  is  prepared  by  the  executive 
officer  and  kept  in  his  oflfice.  Each  man  is  furnished  with 
a  slip  of  paper  called  the  station  billet,  giving  his  number, 
station  to  which  he  is  asssigned,  and  full  information  as  to 
all  his  duties. 

The  office  of  the  executive  officer  is  presided  over  by  the 
ship's  writer,  who  is  one  of  the  most  important  men  in 
the  ship.  In  addition  to  keeping  track  of  the  stations  of  the 
men,  he  keeps  all  records  and  makes  out  all  details  that 
have  to  do  with  the  crew.  For  each  man  on  the  ship, 
there  is  kept  an  enlistment  record,  which  is  begun  wher> 
he  enters  the  service  and  gives  his  history  continuously 
until  his  discharge,  showing  the  various  ratings  that  he 
has  filled  and  his  proficiency  in  them,  his  ability  in  sea- 
manship, ordnance,  signals,  etc.,  his  conduct  and  his  health. 
This  record  is  transferred  with  the  man  from  ship  to  ship, 
and  at  the  end  becomes  a  part  of  the  permanent  files  of 
the  Navy  Department. 

The  following  is  a  sample  of  the  daily  and  weekly  routine 
of  a  man  of  war,  many  small  details  being  omitted: 

DAILY  ROUTINE  IN  PORT 

5.30  A.  M.    Reveille.     All  hands  turn  out  except  those  who 

have   had   night   watches.     30   min.    allowed 

for   stowing   hammocks,    for   coffee,   and  for 

smoking. 
6.00  Turn  to  (viz.,  begin  work).     Scrub  clothes  and. 

clean   ship.     Time   and  opportunity  allowed 

for  bathing,  etc. 
6.30  Send  market  boat  ashore  for  provisions. 

7.00  All    hands.     Men   who    have    been    sleeping-in, 

turn  out. 
7.20  Spread  mess  gear   (viz.,  make  preparation  for 

breakfast). 
7.30  Breakfast.     Crew  dress  in  prescribed  uniform. 

8.00  Colors    (viz.,    hoist    the    ensign,    band    playing 

National  Anthem). 
8.15  Turn    to    (viz.,   resume    work).^    Clean    bright 

work  (brass  and  steel)  of  ship  and  guns. 


170      THE  ORGANIZATION  OF  A  MAN  OF  WAR 

8.45  Sick  call  (viz.,  all  sick  report  to  surgeon). 

9.00  Knock-off    bright    work.     Clear   up    the    decks 

and  make  everything  shipshape,  etc. 

9.30  Quarters  (viz.,  all  hands  go  to  stations  at  guns 

or  elsewhere,  for  muster,  inspection,  and 
drill).  Divisions  are  mustered  and  inspected 
by  their  officers  and  report  made  to  the 
executive  officer  whether  all  are  present. 

9.40  1st  drill  period.     Drills  as  prescribed. 

10.30  2d  drill  period.     Drills  as  prescribed. 

11.00  End  of  forenoon  drills. 

11.20  Stand   by   scrubbed   clothes    (clothes  lines   are 

lowered    and    clothes    removed    from    lines). 
Sweep  decks. 
11.50  Spread  mess  gear  (prepare  for  dinner). 

12.00  Dinner. 

1.00  P.  M.    Turn  to. 

1.30  Afternoon  drill  period. 

2.00  End  of  drill  period.     Sweep  decks. 

4.00  Knock-off    work;    artificers,    carpenters,    black- 

smiths, etc.,  quit  work. 

4.30  Sweep  and  clean  up  decks. 

5.00  Quarters  (muster,  followed  by  setting-up  drill 

for  10  min.). 

5.30  Spread  mess  gear. 

6.00  Supper. 

6.30  Turn  to. 

Sunset  Retreat.    Ensign  lowered,  band  playing  National 

Anthem.  Hoist  boats;  make  all  secure  for 
the  night. 

7.30  Pipe  down  hammocks.     Hammocks  are  taken 

from  place  where  stored  and  slung  ready 
for  use. 

8.00  Chief  engineer,  warrant  officers,  master  at  arms, 

captain  of  hold,  etc.  report  to  e.xecutive 
officer  that  their  respective  parts  of  the  ship 
are  secure.  Master  at  arms  reports  that  the 
galley  fires  and  certain  lights  on  lower  decks 
are  out. 


THE  ORGANIZA TlON  OF  A  MAN  OF  WAR      171 

8.55  Bugle  call,  preliminary  to  tattoo. 

9.00  Tattoo     (bugle).     Pipe    down    for    the    night. 

Turn  in  and  keep  silence.  Muster  anchor 
watch.  Taps. 
Division  of  Time  on  Shipboard. — The  day  on  shipboard  is 
divided  into  watches  which  are  of  4  hr.  each,  except  that  the 
period  from  4  to  8  P.  m.  is  divided  into  two  watches  of  2  hr. 
each,  called  dog  watches.  The  object  of  this  is  to  make  an  odd 
number  of  watches  during  the  24  hr.  so  that  the  starboard 
and  port  watches  of  the  crew  will  not  be  on  duty  at  the  same 
time  every  day.     The  watches  are  designated  as  follows: 

12   noon   to  4  p.  m Afternoon  watch 

4  to  6  p.  M First  dog  watch 

6  to  8  P.  M Second  dog  watch 

8  P.  M.  to  midnight First  watch 

Midnight  to  4  a.  m Mid  watch 

4  to  8  A.  M Morning  watch 

8  A.  M.  to  12,  noon Forenoon  watch 

"the  time  on  shipboard  is  marked  by  strokes  on  the  ship's 
bell,  and  is  expressed  by  the  number  of  bells  (strokes)  that 
have  been  struck;  thus,  1  bell  is  one  stroke  of  the  bell, 
6  bells  is  six  strokes  of  the  bell,  and  so  on.  Counting  from 
12  o'clock,  noon,  which  is  8  bells,  the  half  hours  through 
the  day  and  night  run  as  follows: 

12..30  P.  M 1  bell  7.30  p.  m 7  bells 

1.00  P.  M 2  bells     .     8.00  p.  M Shells 

1.30  P.  M 3  bells  8.30  p.  m 1  bell 

2.00  P.  M 4  bells  9.00  p.  m 2  bells 

2.30  P.  M 5  bells  9.30  p.  m 3  bells 

3.00  p.  M 6  bells        10.00  p.  m 4  bells 

3.30  P.  M 7  bells        10.30  p.  m 5  bells 

4.00  p.  M 8  bells        11.00  p.  m 6  bells 

4.30  P.  M 1  bell  11.30  p.  m 7  bells 

5.00  P.  M '.  .  .2  bells        12  midnight 8  bells 

5.30  p.  M 3  bells        12.30  a.  m 1  bell 

6.00  p.  M 4  bells  1.00  a.  m 2  bells 

6.30  p.  M 5  bells  1.30  a.  m 3  bells 

7.00  p.  M 6  bells        and  so  on  as  before 


172       THE  ORGAXIZA  TION  OF  A  MAN  OF  WAR 

BRIEF  NOTES  AS  TO  ETIQUETTE  OF  A  MAN  OF  WAR 

The  following  brief  notes  will  be  of  value  to  a  recruit 
unfamiliar  with  the  customs  of  the  Navy,  and  may  be  of 
interest  to  others: 

1.  In  saluting  an  officer,  an  enlisted  man  should  stand 
at  attention  and  touch  his  cap.  Attention  is  an  erect  posi- 
tion with  both  heels  together. 

2.  He  should  always  salute  when  addressing  an  officer 
and  when  addressed  by  him.  Also  when  meeting  him  on 
shipboard  or  on  shore,  and  this  whether  he  is  in  uniform 
or  not. 

3.  When  an  officer  is  moving  about  the  ship  in  the  per- 
formance of  his  duty,  it  is  not  required  that  men  shall 
salute  him  every  time  he  passes,  nor  are  men  who  are  them- 
selves actually  at  work  expected  to  stop  their  work  to  salute. 
But  it  is  always  better  to  show  an  excess  of  courtesy  in  this 
matter  than  a  lack  of  it. 

4.  When  the  commanding  officer  passes  along  the  deck, 
all  men  near  whom  he  passes  should  stand  at  attention 
and  salute. 

5.  When  the  commanding  officer  leaves  the  ship  or 
comes  on  board,  in  uniform,  the  signal  for  "silence"  is 
sounded  on  the  bugle  and  everybody  on  deck  stands  at 
attention. 

6.  The  same  ceremony  is  observed  for  an  officer  from 
another  ship  making  an  official  visit. 

7.  When  the  ensign  (national  flag)  is  hoisted  at  8  A.  M. 
or  hauled  down  at  sunset,  the  band  plays  the  "Star  Spangled 
Banner"  and  all  officers  and  men  face  aft  (toward  the  flag) 
and  stand  at  attention.  As  the  flag  reaches  the  peak,  in 
hoisting,  or  the  rail,  in  lowering,  all  salute.  The  flag  is 
sometimes  called  the  flag,  sometimes  the  ensign,  and  some- 
times the  colors. 

8.  When  one  ship  of  war  passes  near  another  (of  any 
nationality),  the  call  for  "silence"  is  sounded  by  bugle,  and 
all  men  on  deck  face  toward  the  side  on  which  the  other  ship 
is  to  be  passed  and  stand  at  attention. 

9.  All  officers  and  men  coming  on  to  the  quarter  deck 
face  toward  the  colors  and  salute. 


THE  CLASSIFICATION  OF  WAR  SHIPS       173 

10.  Men  in  a  boat  which  is  lying  alongside  the  ship  stand 
up  and  salute  as  an  officer  passes  in  another  boat.  When 
a  boat  is  in  charge  of  a  coxswain  only  the  coxswain  salutes* 

11.  In  the  case  of  a  squad  of  men  in  charge  of  one,  only 
the  man  in  charge  salutes. 

12.  Petty  officers  are  entitled  to  be  treated  with  respect^ 
but  are  not  saluted. 

13.  In  cases  where  an  accommodation  ladder  is  shipped 
on  each  side,  enlisted  men  use  the  port  side,  the  starboard 
ladder  being  reserved  for  officers. 

14.  Except  on  duty,  enlisted  men  shall  keep  clear  of 
the  starboard  side  of  the  quarter  deck,  this  being  reserved 
for  the  captain  and  the  officers  of  the  deck. 

15.  Men  given  an  order  by  an  officer,  stand  at  attention,. 

salute,  and  give     "Aye,  Aye,    Sir!"   and  then  execute  the 

order  promptly. 

Note. — The  term  "Aye,  Aye''  is  often  used  incorrectly  in  reply  to  a  questioiiV 
It  is  not  at  all  the  same  thing  as  "Yes,"  but  is  au  expression  "of  readiness  to 
obey.     In  other  words,  it  is  the  response  to  an  order,  not  to  a  question. 

16.  A  man  on  shipboard  wishing  to  see  an  officer,  goes 
to  the  place  appointed  for  communicating  with  the  officer 
of  the  deck  (this  place,  wherever  it  may  be,  is  technically 
called  the  mast)  and  states  his  wishes.  If  the  officer  of  the 
deck  considers  it  proper  to  do  so,  he  sends  for  the  officer 
who  is  wanted.  The  mast  is  the  place  for  formal  communi- 
cation between  officers  and  men,  as  for  example,  where  a 
man  has  a  grievance  and  wishes  to  see  the  captain  or  execu- 
tive. Similarly,  men  charged  with  offenses  are  brought  to 
the  mast  and  their  cases  are  investigated  there". 


THE  CLASSIFICATION  OF  WAR  SHIPS 

General  Considerations. — The  weight  that  a  ship  of  given 
size  will  carry,  and  still  float,  is  limited,  while  the  amount 
of  weight  that  we  would  like  to  make  her  carry,  in  armor, 
armament,  engines,  and  coal  supply,  is  practically  unlimited. 
This  being  the  case,  we  are  compelled  to  accept  a  compro- 
mise, the  nature  of  which  will  depend  on  the  purpose  for 
which  the  particular  ship  in  question  is  to  be  used.     If  we 


174       THE  CLASSIFICATION  OF  WAR  SHIPS 

give  her  the  heaviest  guns  and  thickest  armor,  we  shall 
have  comparatively  little  weight  remaining  for  engines  and 
coal.  "Very  well,"  we  say,  "we  want  this  ship  for  fighting, 
not  for  running  away.  Let  us  give  her  first  of  all  guns  and 
armor;  and  then  do  the  best  that  can  be  done  in  the  way 
of  speed  and  coal  supply."  Thus  we  get  the  battle  ship. 
But  suppose  that  we  want  a  ship  not  to  oppose  the  fighting 
ships  of  the  enemy,  but  to  avoid  these  and  to  chase  and 
capture  her  fleetest  merchant  steamers;  such  a  ship  must 
carry  nearly  all  her  weight  in  powerful  engines  and  large 
coal  supply.  She  needs  few  guns  and  no  armor.  This  is 
a  commerce-destroying  cruiser.  Suppose,  again,  that  we  wish 
to  strike  a  mean  between  these  two  extremes,  preserving  in  a 
considerable  measure  the  fighting  qualities  of  the  battle  ship 
and  associating  them  with  a  speed  and  coal  supply  approxi- 
mating to  those  of  the  fast  cruiser;  this  gives  us  the  armored 
cruiser,  powerful  enough  to  give  a  good  account  of  herself  in 
battle,  even  if  obliged  to  fight  a  battle  ship,  but  able,  as  a 
rule,  to  avoid  such  odds  by  reason  of  her  speed,  and  able, 
also  by  reason  of  her  speed,  to  overtake  all  but  the  fastest  of 
the  enemy's  cruisers  and  merchant  steamers. 

The  following  classes  of  ships  are  recognized  bj"-  the 
great  Naval  Powers: 

Battle  ships  are  ships  of  large  size,  carrying  the  heaviest 
guns  and  thickest  armor,  but  with  moderate  speed  and 
rather  small  coal  supply.  They  are  designed  to  fight  the 
most  powerful  ships  of  an  enemy,  but  not,  as  a  rule,  to  go 
far  from  a  base.  Such  vessels  can^'  their  heavy  guns  in 
turrets.  A  representative  type  of  this  class  is  the  new  battle- 
ship "Maine"  shown  in  Fig.  1  (a),  which  has  a  displacement 
of  12,500  T.,  and  an  average  speed  of  17  knots.  Diagrams 
{b)  and  (c)  show,  respectively,  the  armor  protection  and  bat- 
teries carried  by  the  ship. 

Armored  cruisers  are  ships  of  large  size  carrying  guns  and 
armor  much  lighter  than  those  of  a  battle  ship,  but  heavier 
than  those  carried  by  any  other  class  of  ship  (except  moni- 
tors). They  have  much  higher  speed  than  battle  ships,  and 
earn*'  sufficient  coal  for  steaming  long  distances  and  opera- 
ting at  a  distance  from  the  base.     They  have  a  wider  range 


THE  CLASSIFICATION  OF  WAR  SHIPS       175 


Ml 


"'"-'.Iris    .'I  1    «i  . 


176       THE  CLASSIFICATION  OF  WAR  SHIPS 

lllll, 


THE  CLASSIFICATION  OF  WAR  SHIPS       177 

of  usefulness  than  any   other  class.     The   Russian    cruiser 
"Gromoboi,"  shown  in  Fig.  2,  is  a  fair  type  of  this  class. 


This  ship  has  a  displacement  of  12,367  T.,  a  speed  of  20  knots, 
and  a  coal-carrying  capacity  of  2,500  T.  It  will  be  noticed 
that  the  distribution  of  armor  on    the  '"Gromoboi"  shown 


178       THE  CLASSIFICATION  OF  WAR  SHIPS 


o|    < 

M-n^ 

o] 

M 

o 

L| 

THE  CLASSIFICATION  OF  WAR  SHIPS       179 

in  Fig.  2  (6)  is  about  the  same  as  on  the  "Maine,"  but  that 
the  armor  on  the  latter  ship  is  much  heavier. 

Protected  cruisers  are  ships  of  moderate  size  with  no 
side  armor,  but  having  their  vital  parts  (engines,  boilers, 
and  magazines)  protected  by  a  curved  deck  of  steel  from 
2  to  4  in.  thick.  They  have  good  speed  and  large  coal 
supply,  with  guns  of  moderate  power,  and  are  designed  for 
cruising  on  distant  stations  in  time  of  peace  and  for  block- 
ading, scouting,  and  commerce  destroying  in  time  of  war. 
They  are  designed  also  for  fighting,  but  not  against  armored 
ships.  The  German  cruiser  "Kaiserin  Augusta,"  diagrams 
of  which  are  shown  in  Fig.  3,  belongs  to  this  class  of  ships. 

Cruisers  and  gunboats  are  ships  of  moderate  and  small 
size,  without  armor  or  armored  deck,  with  moderate  speed 
and  light  guns,  b)ut  often  with  ver^'  large  coal  supply.  They 
are  designed  for  cruising  in  time  of  peace  and  for  blockading 
and  commerce  destroying  in  time  of  war;  also  for  fighting 
against  similar  ships  of  an  enemy.  Ships  of  this  class  are 
often  sheathed;  that  is,  their  bottoms  are  covered  with 
wood,  which  in  turn  is  covered  with  copper,  to  prevent 
the  fouling  and  pitting  to  which  the  bottom  of  a  steel  ship 
is  subjected,  if  not  frequently  docked.  A  sheathed  ship 
can  remain  out  of  dock  for  several  years,  if  necessary. 
They  are  often  fitted  with  masts  and  sails. 

Monitors  are  a  special  type,  confined  almost  entirely  to 
the  United  States  Navy,  resembling  battle  ships  in  guns 
and  armor  and  in  carr>-ing  their  large  guns  in  turrets,  but 
differing  from  all  other  types  of  ships  in  that  they  are  very 
low  in  the  water,  and  thus  present  a  very  small  target.  The 
first  monitor,  designed  by  John  Ericsson,  was  the  forerunner 
of  the  battle  ship.  They  are  effective  fighters  in  smooth 
water,  but  not  in  a  rough  sea,  because  the  waves  break 
over  their  low  decks  and  make  it  impossible  to  work  their 
guns,  and  because  they  have  the  further  peculiarity  of 
rolling  very  rapidly.  They  are  essentially  harbor  defense 
ships.  A  type  of  this  class  of  vessel,  the  U.  S.  S.  "Wyoming," 
is  shown  in  Fig.  4  (a),  (6),  and  (c). 

Torpedo  boats  (Fig.  5)  are  light,  low  craft,  very  long 
and  narrow,  of   great    speed,    made    as   nearly  invisible  as 


180       THE  CLASSIFICATION  OF  WAR  SHIPS 

iiii; 


THE  CLASSIFICATIO.X  OF  WAR  SHIPS       181 


r 


11(1 


ilafc 


182       THE  CLASSIFICATION  OF  WAR  SHIPS 

possible  by  their  shape  and  color.  They  are  armed  with  tor- 
pedoes, and  in  some  cases  with  a  few  light  guns;  they  are 
designed  to  attack  larger  ships  with  torpedoes,  usually 
under  cover  of  darkness.  Torpedo  boats  are,  as  a  rule, 
small  vessels,  their  displacements  varying  from  about 
25  to  250  T.,  and  are  fitted  with  powerful  engines  to  drive 
them  at  the  required  high  speed.  Their  interior  space  is 
consequently  ingeniously  arranged  and  utilized  in  every 
possible  way  to  accommodate  the  crew,  boilers,  engines, 
fuel,  stores,  and  other  equipments.     In  Fig.  6  is  shown  the 


interior  arrangement  of  a  modern  torpedo  boat.  The 
several  compartments  designated  by  numbers  are  as  follows. 
1,  chain  locker;  2,  tank;  S,  torpedo  hoist;  4.  spare  torpedoes; 
5,  shaft  for  war  heads;  6,  crew's  quarters;  7,  magazine;  8,  store- 
room; 9,  coal  bunker;  10,  boilers;  11,  stoke  hold;  12,  main 
engine;' 75,  auxiliary  engine;  14,  magazine;  15,  torpedo 
tube;  16,  wardroom  and 'sick  bay;  17,  storeroom;  18,  mess 
room;  19,  pantry;  20,  6  pdr.  quick-firing  gun;  21,  12  pdr. 
quick-firing  gun;  22,  binnacle;  23,  chart  room;  24,  bridge; 
25,  searchlight. 


184       THE  CLASSIFICATION  OF  WAR  SHIPS 


Torpedo  -  boat  destroyers 

are  greatly  enlarged  tor- 
pedo boats,  with  higher 
speed  and  better  sea-going 
qualities.  Armed  with  tor- 
pedoes, but  carrying  also 
several  guns  of  fair  size, 
this  type  was  evolved  with 
a  view  to  running  down 
and  destroying  the  torpedo 
boats  of  an  enemy.  Being 
large  enough  to  keep  the 
sea  even  in  bad  weather, 
they  can  accompany  a  fleet 
of  battle  ships  and  protect 
them  from  torpedo  boats, 
while  at  the  same  time 
themselves  serving  to  at- 
tack the  enemy  with  tor- 
pedoes. 

Other  ships  that  are  es- 
sential to  a  properly  organ- 
ized navy  are  scout  ships 
(large  and  fast),  colliers, 
supply  ships,  hospital 
ships,  distilling  ships  (to 
supply  the  large  amount 
of  fresh  water  needed  by 
modern  boilers),  repair 
ships,  and  despatch  boats. 

A  squadron  is  a  small 
number  of  ships  under  the 
command  of  one  officer. 

A  fleet  is  several  squad- 
rons grouped  under  the 
command    of  an  admiral. 

A  flotilla  is  a  group  of 
small  craft,  torpedo  boats, 
etc. 


THE  CLASSIFICATIOX  OF  WAR  SHIPS  185 

MAN-OF-WAR  BOATS 

Launches  are  large  heavy  boats  designed  primarily  for 
carrying  cargo  or  for  carrying  large  bodies  of  men  in  landing 
operations. 

Cutters  are  like  launches,  but  much  smaller,  and  are  used 
for  both  cargo  and  passenger  boats;  both  launches  and 
cutters  are  fitted  for  carrying  light  field  guns. 

Whale  boats  are  lighter  than  cutters  and  of  a  different 
model,  being  sharp  at  the  stem  as  well  as  at  the  bow;  they 
are  used  for  miscellaneous  work,  being  light  and  handy. 

Dingies  are  small  boats  pulling  usually  four  oars,  used 
for  light  work  of  any  kind. 

The  barge,  used  only  in  a  flagship,  is  the  personal  boat  of 
an  admiral. 

The  gig  is  the  personal  boat  of  the  captain;  it  is  usually 
a  small  whaleboat. 

Steam  launches  and  steam  cutters  are  boats  of  fair  size 
run  by  steam  and  used  for  the  general  work  of  the  ship. 

In  Fig.  7  are  shown  the  various  rigs  of  man-of-war  boats 
for  sailing,  of  which  (a)  is  the  gaflf  and  boom  rig  used  on 
launches  of  the  U.  S.  Navy;  ib)  is  known  as  sprit  rig;  (c) 
dipping  lug  foresail  and  standing  lug  mainsail;  id)  sljding 
gunter;  (e)  balance  lug;  and  (/)  standing  lug. 

BUGLE  CALLS 

Signals  for  many  of  the  events  of  daily  routine  are  made  by 
bugle  calls.  Each  class  of  boat  has  a  call,  and  the  indi- 
vidual boats  of  the  class  are  distinguished  by  one,  two,  or 
more  blasts  after  the  call:  thus,  the  signal  for  manning  the 
third  cutter  is  the  cutter  call  followed  by  three  blasts. 

Other  bugle  calls  are:  reveille,  tattoo,  taps  mess-gear 
quarters,  retreat,  assembly,  silence. 


(e)  (f) 

Fig.  7 


A^4T^4L  ORDXAXCE  187 

NAVAL  ORDNANCE 

GUNS 

The  guns  carried  on  shipboard  as  a  part  of  the  armament 
of  the  ship  (except  shoulder  pieces  and  revolvers,  which 
are  technically  known  as  small  arms)  are  of  great  variety, 
as  regards  both  size  and  mechanical  principles;  ranging 
from  light  automatic  guns  of  musket  caliber  firing  500  shots 
per  min.,  to  the  monster  13-in.  rifles  of  60  T.  weight,  mounted 
on  a  carriage  of  enormous  strength,  within  a  turret  protected 
by  a  hundred  tons  of  armor,  firing  a  projectile  weighing 
i  T.,  and  burning  500  lb.  of  powder  at  every  round. 

Classification  of  Guns. — All  modern  guns  are  built  up  of 
steel,  and  all  are  rifled  and  breech-loading. 

A  built-up  gun  is  one  in  which  several  layers  of  steel  are 
built  up,  one  over  another,  on  a  principle  to  be  hereafter 
explained. 

A  rifled  gun  is  one  in  which  the  barrel  is  grooved  along 
that  part  of  its  bore  through  which  the  projectile  is  to  be 
driven  by  the  powder  gases,  the  grooves  running  spirally 
along  and  around  the  bore. 

A  breech-loading  gun  is  one  that  is  loaded  from  the 
breech,  the  projectile  being  entered  first  and  pushed  for- 
wards to  the  beginning  of  the  rifled  bore.  The  powder  is 
then  entered,  in  the  rear  of  the  projectile,  and  the  breech 
closed  by  a  heavy  plug  or  block.  The  method  of  fitting 
this  plug,  and  the  mechanical  arrangement  by  which  it 
is  opened  and  closed,  constitute  the  essential  features  of 
the  various  types  of  breech  mechanism  used  with  different 
types  of  guns.  Some  of  these  breech  mechanisms  are 
suitable  only  for  small  guns,  others  only  for  large  ones, 
while  a  few  are  adaptable  to  any  caliber.  The  great  object 
of  most  inventors  has  been  to  obtain  rapidity  of  action;  and 
in  some  types  of  mechanism,  the  operations  of  unlocking  the 
plug,  withdrawing  it  from  the  gun,  and  swinging  it  out  of  the 
way,  are  all  done  by  a  single  sweep  of  a  lever.  These  are 
technically  known  as  rapid-fire,  or  quick-fire,  mechanisms. 
They  are  confined  to  guns  of  7-in.  caliber  and  under. 


188 


NAVAL  ORDNANCE 


In  guns  up  to  and  including  the  5-in.  caliber,  the  powder 
is  commonly  packed  in  a  copper  cartridge  case,  and  the 
base  of  the  projectile  is  forced  into  the  mouth  of  the  case 
and  gripped  there,  forming  a  complete  cartridge  like  that 
for  a  musket  or  a  revolver.  Such  ammunition,  Fig.  1,  is 
technically  known  as  fixed  ammunition.  The  copper  case 
not  only  holds  the  powder,  but  also  prevents  the  escape 
of  gas  to  the  rear  when  the  gun  is  discharged,  thus  doing 
away  with  the  necessity  for  a  special  arrangement  for  this 
purpose  (a  gas  check) ,  which  wall  be  described  in  connection 


Fig.  1 

with  guns  that  do  not  use  cartridge  cases.  The  breech 
mechanism  of  a  gun  using  a  cartridge  case  must  include 
an  extractor  for  withdrawing  the  case  after  firing.  For 
guns  larger  than  5-in.  caliber,  the  powder  is  put  up  in  bags 
and  loaded  separately  from  the  projectile.  Guns  using 
fixed  ammunition  are  called  rapid-fire  guns. 

Other  classes  of  guns  are  machine  guns,  which  are  fired 
rapidly  and  continuously  by  turning  a  crank  or  lever,  the 
cartridges  being  fed  in  through  a  hopper;  automatic  guns 
in  which  the  shock  of  discharge  of  one  cartridge  extracts 


XAVAL  ORDNANCE  1S9 

the  empty  case  and  loads  and  fires  the  next  cartridge,  and 
so  on  indefinitely  as  long  as  the  supply  of  ammunition  holds 
out;  and  semiautomatic  guns  in  which  the  shock  of  dis- 
charge does  a  part  of  the  work  of  the  automatic  guns,  but 
the  loading  is  done  by  hand. 

Principles  of  Gun  Construction. — The  power  of  guns  has 
been  enormously  increased  within  the  last  quarter  century, 
following  upon  the  wonderful  increase  in  the  efficiency  of 
powders,  and  this  has  called  for  a  corresponding  increase 
in  the  strength  of  guns.  The  old-style  gun,  whether  smooth 
bore  or  rifled,  was  made  from  a  single  piece  of  metal — cast 
iron,  wrought  iron,  bronze,  or  steel.  There  is  a  limit  to  the 
possible  strength  of  such  a  gun,  since  after  a  certain  thick- 
ness of  wall  has  been  reached,  no  increase  in  thickness  adds 
anything  to  the  strength  of  the  gun.  This  is  easily  explained. 
When  the  powder  inside  the  gun  explodes,  the  pressure 
developed  is  felt  first  by  the  inner  layers  of  the  metal. 
These  layers  are  expanded  and  transmit  the  strain  to  the 
layers  next  outside  them,  which  in  their  turn  expand  and 
transmit  the  strain  to  the  parts  beyond,  and  so  on.  Thus 
the  successive  layers  into  which  we  may  imagine  the  walls 
of  the  gun  to  be  divided  take  up  the  strain,  not  all  together, 
but  one  after  the  other,  from  inside  out,  each  one  taking 
a  little  less  than  the  one  inside.  When  the  walls  are 
sufficiently  thick  for  the  extreme  outer  layer  to  feel  the 
strain  just  before  the  inner  layer  is  ruptured,  it  will  be  use- 
less to  add  more  layers,  because  these  would  not  take  any 
part  in  resisting  the  strain  until  the  inner  layers  had  been 
stretched  beyond  the  rupturing  point. 

In  the  modem  system  of  gun  making,  the  gun  is  built 
up  of  hoops  or  bands  of  tempered  steel  shrunk  one  upon 
another,  on  what  is  called  the  principle  of  initial  tensions. 
Suppose  that  we  have  two  hoops  of  steel,  one  larger  than 
the  other  and  of  st:ch  dimensions  that  the  inner  diameter 
of  the  larger  is  slightly  less  than  the  outer  diameter  of  the 
smaller.  If  we  expand  the  larger  by  heat,  slip  it  over  the 
smaller  one,  and  allow  it  to  cool  and  set,  the  result  will  be 
two-fold:  first,  the  outer  tube  will  be  stretched  and  thus 
put  under  an  initial  tension;  and  second,  the  inner  tube 


ISO 


NAVAL  ORDNANCE 


NAVAL  ORDNANCE  191 

will  be  more  or  less  compressed.  In  this  condition,  the 
first  effect  of  a  pressure  from  the  inside  will  be  to  expand 
the  inner  tube,  relieving  the  compression  without  putting 
any  strain  upon  the  metal.  By  the  time  it  has  enlarged 
sufficiently  to  begin  to  feel  a  strain,  the  outer  tube  will 
feel  the  effect  of  the  enlargement  and  will  resist  this  by 
reason  of  its  own  initial  tension,  and  thus  both  tubes  will 
act  together  in  resisting  the  pressure  from  within.  The 
laws  that  govern  the  beha\'ior  of  steel  under  these  conditions 
are  so  well  known  that  it  is  possible  to  calculate  the  exact 
amount  of  shrinkage  required  to  make  the  various  parts 
of  a  gun  act  together  to  the  best  advantage,  and  instead 
of  using  two  layers  only,  we  can  use  as  many  as  we  like  and 
put  them  together  in  such  a  way  that  all  will  act  together 
in  resisting  the  pressure  in  the  bore.  Thus  the  gun  is  made 
very  much  stronger  than  would  be  possible  if  it  were  in  a 
single  part. 

Another  very  great  advantage  of  building  up  the  guns 
in  this  way  is  that  all  the  parts,  being  small,  can  be  more 
perfectly  tempered  and  annealed,  and  any  defects  in  them 
can  be  more  easily  detected,  than  if  they  were  larger. 

In  practice,  three  layers  are  commonly  used,  as  shown 
in  Fig.  2.  The  inner  laj'er  is  a  tube,  running  the  whole 
length  of  the  gun  and  forming  the  bore  and  chamber.  Over 
the  after  part  of  this  is  shrunk  the  heavy  jacket,  and  over 
this,  a  layer  of  hoops.  The  hoops  are  continued  forwards 
of  the  jacket  along  the  tube,  only  two  layers  being  needed 
at  this  part,  as  the  pressure  is  lower  here  than  it  is  toward 
the  breech.  The  dotted  curve  above  the  gun  shows  the 
way  in  which  the  pressure  varies  throughout  the  bore.  It 
will  be  seen  that  the  thickness  of  the  wall  of  the  guns  corre- 
sponds in  a  general  way  with  the  shape  of  this  curve. 

Gun  Steel. — The  steel  of  which  guns  are  made  is  of  the 
very  finest  quality  known,  and  a  quality  that,  25  yr.  ago, 
could  not  have  been  produced  in  the  world.  It  is,  indeed, 
one  of  the  most  interesting  facts  in  connection  with  the  extra- 
ordinary development  of"  our  Navy  that  the  demand  for  a 
constantly  improving  quality  of  material  has  led  to  improve- 
ments in  the  manufacture  of  steel  far  exceeding  those  that 


192  A'.4T'.4L  ORDXAXCE 

might  have  been  expected  from  the  demands  of  ordinary 
industries. 

Properties  of  Steel. — In  the  popular  conception,  the  most 
important  characteristic  of  steel  is  its  tensile  strength;  the 
strength,  that  is  to  say,  with  which  it  resists  rupture.  In 
gun  steel,  this  is  less  important  than  its  elastic  strength,  or 
the  strength  with  which  it  resists  permanent  deformation 
or  change  of  form.  So  long  as  a  gun  is  exposed  only  to  pres- 
sures below  its  elastic  strength,  or  "within  its  elastic  limit," 
it  expands  to  the  pressure  and  then  returns  to  its  original 
shape,  acting  like  a  great  spring;  and  it  may  be  repeatedly 
subjected  to  such  pressures  without  being  in  the  least  weak- 
ened or  deformed.  But  if  it  is  once  subjected  to  pressure 
beyond  its  elastic  limit,  it  takes  on  a  permanent  enlargement, 
which  not  only  deforms  it,  but  weakens  the  metal. 

Other  important  qualities  in  gun  steel  are  toughness, 
ductility,  and  hardness,  the  last-named  quality  being  espe- 
cially important  in  the  bore,  which  is  called  upon  to  resist 
the  wear  arising  from  the  motion  of  the  projectile  and  the 
friction  of  the  powder  gases  as  they  rush  down  the  bore. 
The  friction  of  these  gases,  combined  no  doubt  with  some 
chemical  action  that  is  intensified  by  the  high  temperature, 
produces  a  scoring  of  the  bore  that  is  technically  known  as 
erosion,  and  which  gradually  enlarges  the  bore  and  thus 
reduces  the  accuracy  of  the  gun.  The  harder  the  steel  of 
the  bore,  the  less  it  is  eroded. 

Ductility  is  the  opposite  of  brittleness,  and  is  that  quality 
which  causes  the  steel  to  stretch  before  rupturing,  instead 
of  flying  apart  suddenly  and  without  warning,  like  glass  and 
similar  substances.  Steel  is  tested  by  breaking  test  pieces 
in  a  testing  machine  under  varying  tensions  and  noting: 
(a)  the  tension  at  which  it  ceases  to  spring  back  if  the 
tension  is  released,  or  the  elastic  limit;  (b)  the  tension  at 
which  it  breaks,  or  the  tensile  strength;  (c)  the  amount  by 
which  it  is  stretched  in  breaking,  or  the  elongation;  (d)  the 
amount  by  which  the  cross-sectional  area  is  reduced  by 
stretching,  or  the  reduction  of  area. 

Composition  of  Steel. — Steel,  as  known  to  metallurgists 
until   within  quite  recent  years,  was  an  alloy  of  iron  and 


NAVAL  ORDXAXCE 


193 


carbon,  the  percentage  of  the  carbon  varying  considerably, 
but  being  always  less  than  2%.  Steel  with  .3%  to  .5% 
is  a  low,  soft,  or  mild  steel;  steel  having  from  1%  to  2%  is 
high  steel.  Low  steels  approach  wrought  iron  and  high 
steels  cast  iron,  in  their  characteristics. 

It  has  recently  been  found  that  other  substances  can  be 
advantageously  added  to  the  alloy  of  iron  and  carbon. 
The  most  important  of  these  substances  for  gun  steel  is 
nickel,  about  3%  of  which  is  used   in  the  so-called  nickel 


Pi  ^;i 


^ 


■f— =^' 


Fig.  3 
steel,  which  is  now  very  generally  used  for  guns  and  armor. 
This  amount  of  nickel  takes  the  place  of  a  part,  but  not  the 
whole,  of  the  carbon.     The  nickel  increases  both  the  tensile 
and  the  elastic  strength. 

The  Treatment  of  Gun  Steel. — Steel  ingots  for  guns  are 
first  cast,  then  forged  under  a  hammer  or  press  into  the 
right  shape  for  which  they  are  designed.     Fig.  3  shows  an 


194  NAVAL  ORDNANCE 

ingot  in  the  5,000-ton  forging  press  of  the  Bethlehem  Steel 
Co.  As  in  the  forging  irregular  strains  may  be  set  up, 
the  next  process  is  one  of  annealing;  this  consists  in  heating 
the  ingot  to  a  red  heat  and  allowing  it  to  cool  slowly.  In 
this  process,  the  particles  of  the  metal  gradually  readjust 
themselves  and  settle  into  a  condition  of  uniform  crystal- 
lization and  of  freedom  from  strain.  The  forging  is  then 
tempered  in  oil;  that  is  to  say,  it  is  heated  to  a  high  tem- 
perature and  plunged  into  a  bath  of  oil,  which  cools  it  rapidly, 
and,  in  the  rearrangement  of  structure  that  results,  modifies 
all  its  characteristics,  increasing  very  greatly  the  hardness, 
toughness,  and  elasticity,  but  reducing  the  ductility;  or, 
in  other  words,  rendering  it  brittle.  To  restore  the  ductility 
and  at  the  same  time  to  relieve  any  internal  strains  that 
may  have  been  set  up  within  the  mass  by  uneven  cooling 
in  the  process  of  tempering,  the  ingot  is  now  reannealed. 
This  final  process,  to  a  certain  extent,  undoes  the  effects 
of  the  tempering;  but  whereas  it  reduces  only  a  little  the 
elastic  and  tensile  strength,  it  almost  entirely  restores  the 
ductility,  and  it  also  relieves  the  strains  produced  in  tem- 
pering. By  reducing  the  hardness,  it  also  prepares  the 
ingot  for  the  machining  to  which  it  is  next  subjected. 

Manufacture  of  the  Guns. — Most  of  the  guns  for  the  Navy 
are  manufactured  at  the  Washington  gun  factory,  but  con- 
tracts have  in  some  cases  been  made  with  private  firms  such 
as  the  Bethlehem  and  Midvale  Steel  Companies  for  delivering 
the  guns  complete.  The  various  parts  of  the  gun  are  received 
at  the  factory  in  the  shape  of  rough  ingots  for  the  tube,  jacket, 
and  hoops.  The  first  operation  is  to  rough  bore  and  turn 
them,  very  caretul  inspection  being  made  during  these  and 
subsequent  operations  for  imperfections  of  any  kind  in  the 
metal.  The  shrinkage  surfaces  are  then  finished  very  care- 
fully to  dimensions  that  have  been  determined  by  calculations, 
the  calculations  being  based  on  the  known  characteristics  of 
the  particular  ingots  to  be  used.  The  variations  allowed  in 
dimensions  of  the  shrinkage  surfaces  are  never  more  than  .001 
or  .002  in.  The  amount  of  shrinkage  is  greater  for  large  than 
for  small  guns,  and  greater  for  the  outer  parts  (hoops  over 
jacket)  than  for  the  inner  parts  (jacket  over  tube). 


NAVAL  ORDNAXCE 


195 


The  outer  surface  of  the  tube  and  the  inner  surface  of 
the  jacket  having  been  accurately  finished  to  the  shrinkage 
dimensions,  the  tube  is  placed  in  the  shrinkage  pit,  muzzle 
down,  and  the  jacket  in  a  hot-air  furnace,  where  it  is  sub- 
jected to  a  temperature  of  600°  F.  for  a  length  of  time  that 


Fig.  4 

experience  has  shown  to  be  necessary.  It  is  thus  expanded 
sufficiently  to  admit  of  slipping  it  over  the  tube.  It  is 
then  lifted  by  a  crane  and  swung  into  position  directly 
above  the  end  of  the  tube,  Fig.  4,  where  it  is  carefully  cen- 
tered and  then  lowered  into  place.     In  the  meantime    a 


196  A^4F.4L  ORDNANCE 

stream  of  water  has  been  started  inside  the  tube;  this  keeps 
the  tube  cool  and  causes  the  jacket  to  cool  from  the  inside 
out.  As  it  cools  it  grips  the  tube,  compressing  it  slightly, 
as  already  explained,  and  at  the  same  time  taking  on  a 
slight  initial  tension  itself.  When  all  parts  are  cool,  the 
tube  and  jacket,  which  now  form  one  piece,  are  lifted  and 
placed  in  a  lathe,  where  the  outer  surfaces  are  finished  to 
the  proper  dimensions  for  receiving  the  hoops.  The  hoops 
are  placed  on  in  substantially  the  same  manner  as  the  jacket. 

At  certain  points  of  the  construction,  locking  bands,  or 
hoops,  are  used,  so  fitted,  either  with  screw  threads  or  with 
shoulders,  upon  the  other  parts,  as  to  lock  all  the  various 
parts  together  so  that  all  shall  help  to  resist  longitudinal 
strains,  or  strains  in  the  direction  of  the  axis  of  the  gun. 
These  locking  arrangements  are  shown  in  Fig.  2. 

Rifling  the  Bore. — The  final  operation  is  that  of  cutting 
the  grooves  of  the  rifling.  This  is  done  by  a  set  of  cutters 
mounted  on  a  long  rifling  bar  connected  with  a  mechanism 
that  moves  the  cutters  down  the  bore  and  at  the  same 
time  revolves  them,  the  motions  of  translation  and  rotation 
being  regulated  automatically  to  give  the  required  twist 
to  the  grooves.  Several  grooves  are  cut  at  one  time,  and 
the  cutters  are  then  revolved  as  much  as  necessary  to  cut 
another  set. 

Star  Gauging. — When  the  gun  is  finished,  the  bore  is 
carefully  meastired  by  a  star  gauge.  This  is  one  of  the 
most  important  instruments  used  in  connection  with 
ordnance,  as  it  affords  the  only  method  of  measuring  the 
diameter  of  the  bore  of  a  gun — a  measurement  that  is  often 
wanted  in  service  when  it  is  thought  that  a  gun  may  have 
been  injured  by  some  accident;  such,  for  example,  as  the 
explosion  of  a  shell  in  the  bore. 

The  star  gauge  consists  of  a  long  brass  sleeve  made  in 
several  sections  that  can  be  screwed  together  to  give  the 
length  required  for  working  at  any  part  of  the  bore.  On 
the  end  of  tliis  sleeve  is  a  head  carrying  three  radial  points 
of  tempered  steel,  connected  with  a  wedge  inside  the  head 
in  such  a  way  that  as  the  wedge  is  moved  forwards  or 
backwards,   the   points  are  forced  out  or  drawn  in.     The 


NAVAL  ORDNANCE 


197 


wedge  is  actuated  by  a  long  rod 
running  inside  the  sleeve  and 
having  a  handle  at  the  outer  end. 
This  handle  has  a  pointer  that 
moves  along  a  scale  on  the  sleeve, 
indicating  how  far  the  rod  (and 
hence  the  wedge)  is  moved  in  or 
out.  The  bevel  of  the  wedge 
being  known,  this  motion  back 
and  forth  gives  the  measure  of 
the  motion  of  the  points  in  and 
out.  For  each  caliber  of  gun, 
there  is  a  set  of  standard  points; 
and  in  preparing  the  star  gauge 
for  use,  these  points  are  adjusted 
so  that  they  just  fit  the  diameter 
of  a  standard  ring  when  the  scale 
on  the  rod  is  at  zero.  The  gauge 
is  then  put  in  the  gun  and  care- 
fully fixed  at  the  point  where  the 
measurement  is  desired.  The 
points  are  then  forced  out  against 
the  bore,  and  the  reading  of  the 
scale  (which  is  fitted  with  a  ver- 
nier) gives  the  diameter.  In  star 
gauging  a  gun,  a  measurement  is 
usually  made  at  every  inch  of  its 
length. 

In  Fig.  5  are  shown  the  details 
of  a  gun  as  loaded  and  ready  for 
firing.  Although  not  shown  in 
the  figure,  the  greater  part  of  the 
length  of  the  gun  is  given  up  to 
the  rifled  bore.'  In  rear  of  the 
rifling,  the  bore  is  enlarged  to 
form  the  powder  chamber,  and  in 
rear  of  this  comes  the  threaded 
screw  box,  in  which  the  breech 
plug  is  held.     At  the  rear  end  of 


198 


.V.4F.4L  ORDNANCE 


the  rifled  bore  is  a  slight  slope  against  which  the  rotating 
band  of  the  projectile  (to  be  described  hereafter)  brings  up 
when  the  projectile  is  pushed  into  its  seat.  This  is  the  band 
slope,  and  a  little  in  rear  of  this  is  the  chamber  slope,  carrying 
the  diameter  up  to  that  of  the  chamber.  At  the  forward  end 
of  the  screw  box  is  the  gas-check  slope,  against  which  .the 
gas  check  is  seated  when  the  bore  is  closed. 

BREECH  MECHANISMS  OF  GUNS 


Breech  Blocks. — In  all  guns  of  and  above  the  3-in.  caliber  the 
same  general  system  is  used  for  closing  the  breech;  this  is  the 
French,  or  interrupted-thread,  system  shown  in  Fig.  1  (a)  and 

(6).  On  the  outside  of 
the  cylindrical  block,  is 
a  male  screw  thread  en- 
gaging a  female  thread 
in  the  screw  box  of  the 
gun.  If  both  of  these 
threads  were  continu- 
ous, the  block  could 
only  be  seated  by 
screwing  it  in  with  a 
great  number  of  turns. 
To  avoid  this,  the 
threads  are  inter- 
rupted, or  slotted, 
over  several  sections 
of  the  circumference, 
as  shown  in  the  fig- 
ure. By  bringing  the 
threaded  parts  of 
the  plug  opposite  the 
blanks  of  the  screw 
box,  the  plug  may  be 
pushed  nearly  into 
its  seat,  where  by 
turning  it  through  a  part  of  a  circle,  the  threads  are  engaged, 
and  the  plug  is  forced  home  with  considerable  pressure,  which 


NAVAL  ORDNANCE 


199 


holds  it  up  rigidly  against  the  force  of  the  powder  gases  when 

the  gun  is  fired. 

Several  modifications  of  the  above  general  principle  are 

in  use,  having- for  their  object  increased  rapidity  of  action. 

Thus,  the  Elswick  breech  plug,  Fig.  2,  is  conical,  this  shape 

giving  the.  advantage  that  the  plug  can  be  swung  around 

to  the  side  at  the 
same  time  that  it  is 
being  withdrawn; 
in  other  words,  its 
motion  from  the 
first  is  on  the  arc  of 
a  circle. 

In  the  Welin 
breechblock,  Fig. 3, 
the  whole  surface  Is 
divided  into  three 
parts,  and  each 
part  is  divided  into 
four  steps,  of  which 

three  steps  are  threads  of  different  lengths,  and  the  fourth 

step  is  blank.     By  placing  the  block  as  shown  in  the  figure,  it 

can  be  pushed  in,  and  to 

lock  it  calls  only  for  a 

turn  through  one-twelfth 

of  the  circumference. 

With   this   arrangement, 

the  threads  cover  a  much 

larger  proportion  of  the 

surface  of  the  block  than 

with  other  systems,  and 

therefore,  for  a  given 

strength  a  shorter  and 

lighter  block  can  be  used. 

In  the  small  calibers,  moreover  the  use  of  a  short  block  makes 

it  possible  to  swing  the  block  around  as  in  the  Elswick  sys- 
tem, without  hitting  the  opposite  side  of  the  screw  box. 

Other  systems   of   breech   closure   are   the   Hotchkiss,   in 

which  a  block  is  thrown  up  across  the  breech  for  closing  and 


200  .V.4I'.4L  ORDXANCE 

allowed  to  fall  by  its  own  weight  for  opening,  and  the 
Driggs-Schroeder  in  w^hich  a  block  is  pivoted  in  rear  of  the 
breech  and  turned  up  and  down  for  closing  and  opening, 
the  last  motion  of  closing  bringing  into  play  a  beveled 
surface  that  forces  the  cartridge  home. 

Breech  Mechanisms. — In  any  mechanism  using  a  slotted 
screw  block,  there  are  certain  operations  that  must  be 
performed.  For  opening,  the  block  must  be  rotated  suffi- 
ciently to  unlock  the  threads,  withdrawn  to  the  rear  as  far 
as  may  be  necessary  for  clearing  the  screw  box,  and  swung 
ofif  to  one  side,  leaving  the  breech  of  the  gun  clear  for  load- 
ing. In  closing  the  block,  the  operations  are  reversed. 
In  the  earliest  breech-loading  guns,  the  block  was  rotated 
by  a  lever,  pulled  to  the  rear  by  an  entirely  independent 
motion,  and  swung  to  the  side  by  a  third  motion.  A 
mechanism  was  soon  devised  by  which  the  rotation  and 
withdrawal  of  the  plug  were  so  related  to  each  other  that 
the  continuous  turning  of  a  crank  accomplished  both,  the 
motion  of  the  crank  actuating  a  miter-wheel,  which  first 
rotated  and  then  withdrew  the  block  without  any  change 
to  the  crank-action.  It  was  a  simple  step  to  add  the  third 
motion,  that  of  swinging  the  block;  and  the  resulting 
mechanism,  in  which  the  block  is  rotated,  withdrawn,  and 
swung  clear  by  the  continuous  turning  of  a  crank,  is  in  use 
in  most  of  our  turret  guns  at  present. 

This  system  is  not  rapid  enough  for  guns  of  smaller 
caliber,  and  is  replaced  in  such  guns  by  various  systems, 
known  by  the  names  of  their  inventors,  in  which  all  the 
operations  of  working  the  breech  block  are  accomplished 
by  a  single  sweep  of  a  lever.  The  systems  used  in  the 
United  States  Navy  are  the  Haeseler,  Dashiell,  Fletcher, 
Elswick,  Vickers,  and  Maxim-Nordenfelt,  for  guns  of  3-in. 
caliber  and  above,  and  the  Hotchkiss,  Driggs-Schroeder, 
and  Maxim-Nordenfelt  for  small  guns  only.  Space  does  not 
permit  an  attempt  at  describing  these,  but  it  is  not  difficult 
to  understand  that  there  are  many  combinations  of  gears, 
cams,  and  levers  by  which  a  single  movement  of  an  arm 
may  first  rotate  a  block,  then  withdraw  it,  and  finally  swing 
it  to  the  side. 


.V.4T'.4L  ORDXAXCE 


201 


Gas  Checking. — When  a  great  gun  is  fired,  the  pressure 
in  the  bore  may  be  anywhere  from  10  to  20  T.  to  the  sq.  in. 
Under  this  pressure,  the  tendency  of  the  heated  gases  to 
escape  is  such  that  they  seek  any  minute  channel  that 
may  be  open  to  them  and  rush  through  this  with  tremendous 
violence.  The  problem  of  sealing  even^  such  channel  is 
thus  of  great  importance,  and  every  system  of  breech 
closure  must  provide  for  an  absolutely  tight  joint  around 
the  block,  while  at  the  same  time  leaving  the  block  per- 
fectly free  to  open.     Where  a  cartridge  case  is  used,   the 

case  itself  serves  as  a  gas-check,  the  ^^— _- ^ 

elastic  metal  of  the  case  being  set 
out  tightly  against  the  walls  of  the 
gun. 

With  guns  that  do  not  use  fixed 
ammunition,  the  De  Bange  system 
of  gas  checking,  or  obturation,  is 
universally  adopted.  In  this  sys- 
tem, Fig.  4,  which  is  the  invention 
of  a  French  officer,  a  tight  joint  is 
made  at  the  forward  end  of  the 
breech  block  B  by  a  plastic  pad  a 
composed  of  asbestos  and  tallow. 
This  pad  is  in  the  shape  of  a  ring 
and  is  carried  on  the  stem  c  of  the 
mushroom  w  lying  in  the  assembled 
mechanism,  between  the  after  face 
of  the  mushroom  head  and  the  for- 
ward face  of  the  breech  plug.  The  pad  is  enclosed  by  two 
steel  rings,  which  help  to  keep  it  in  shape.  The  surface  of  the 
pad  is  slightly  beveled,  as  is  also  the  gas-check  seat  in  the 
gun;  and  the  action  of  the  threads  on  the  block  as  the  latter 
is  rotated  in  closing,  jams  the  pad  firmly  up  against  the  seat 
forming  a  tight  joint,  which  is  made  tighter  when  the  gun  is 
fired  by  the  pressure  of  the  gases  forcing  back  the  mushroom 
and  squeezing  the  pad  between  the  mushroom  and  the  block. 

Firing. — Guns  are  fired  by  primers,  which  are  worked  by 
either  electricity  or  percussion.  Primers  for  fixed  ammuni- 
tion are  inserted  in  a  recess  at  the  base  of  the  cartridge 


Fig.  4 


202 


NAVAL  ORDNANCE 


case.  For  ordinary  ammunition,  they  are  inserted  in  a 
lock  that  screws  on  to  the  rear  end  of  the  mushroom  stem. 
A  vent  running  through  the  mushroom  admits  the  flame 
from  the  primer  to  the  chamber,  where  it  ignites  the  charge 
(see  Fig.  4) .  As  both  brown  powder  and  smokeless  powder 
are  very  slow  of  ignition,  a  considerable  quantity  of  black 
powder  is  used  in  the  base  of  the  charge.  This  is  called 
the  ignition  charge.  All  primers  are  vent-sealing;  that  is, 
they  are  made  of  metal  thin  enough  to  be  expanded  against 
the  walls  of  the  recess  that  contains  them,  and  thus  prevent 
the  escape  of  gas  around  them. 

Figs.  5,  6,  and  7  show  the  several  forms  of  primers  at 
present  used  in  the  United  States  Navy.  In  Fig.  5  is  repre- 
sented   the    ordinary    form    of    percussion    primer   used    in 


Fig.  5 


cartridge  cases  of  fixed  ammunition.  The  striking  of  the 
hammer  on  the  primer  explodes  the  fulminate  of  mercury 
immediately  under  it,  and  the  flame  from  this  ignites  the 
black  powder  in  the  magazine. 

The  ordinary  form  of  electric  primer  for  fixed  ammunition 
is  shown  in  Fig.  6.  The  electric  circuit,  open  at  the  firing 
key,  is  connected  with  a  firing  pin,  which  makes  contact 
at  a  when  the  breech  is  closed.  From  a,  the  circuit  continues 
through  the  insulated  metal  base  plug  to  the  ring  c,  thence 
through  the  platinum  wire  bridge  c  to  a  second  ring  d,  which 
is  in  electrical  contact  with  the  cup  that  forms  the  base 
of  the  powder  pocket.     This  cup,  in  turn,  communicates 


NAVAL  ORDNANCE  203 

with  the  walls  of  the  primer  and  then  with  the  walls  of 
the  gun,  and  the  gun  is  connected  to  the  hull  of  the  ship; 
that  is  (electrically  speaking)  to  earth.  As  the  circuit  is 
grounded  on  the  other  side  of  the  firing  key,  the  closing 
of  this  key  completes  the  circuit,  raises  the  wire  of  the 
bridge  e  to  incandescence,  and  ignites  a  wisp  of  guncotton 
that  is  wrapped  around  the  wire,  thus  firing  the  primer 
and  igniting  the  charge. 


■■....^.^■s,^,^,^.-,^^'.^,..,„„,^  ys  \  V^'SSggg 


l 


Fig.  7 

Fig.  7  shows  a  combination  primer  (percussion  and  electric), 
the  principle  of  which  will  be  readily  understood  from  what 
has  preceded.  This  primer  is  used  for  ordinary'  breech-load- 
ing guns  where  the  flame  has  to  make  its  way  through  a 
long  vent,  and  since  this  calls  for  a  considerable  quantity  of 
powder,  the  primer  is  necessarily  much  longer  than  the  ordi- 
nary. The  combination  primer  for  fixed  ammunition  is 
identical  with  this  in  all  respects  except  the  length. 

PROJECTILES 

The  projectiles  for  rifled  guns  are  elongated  and  are  held 
point  foremost,  as  they  drive  through  the  air,  by  the  rapid 
rotation  about  their  axis,  imparted  to  it  from  the  twist  of 
the  rifling.  To  make  the  projectile  engage  the  rifling,  it 
is  fitted  with  a  rotating  band  c,  c.  Fig.  1,  of  soft  copper  a 
little  larger  than  the  bore  of  the  gun,  the  projectile  itself 
being  a  little  smaLcr  than  the  bore.  When  the  projectile 
is  loaded,  it  passes  freely  through  the  enlarged  powder 
chamber  and  enters  the  bore,  but  the  band  brings  up  against 
the  band  slope  and  prevents  the  projectile  going  farther. 
When  the  gun  is  fired,  the  pressure  of  the  gases  drives  the 
soft  band  through  the  grooves,  and  sends  it  whirling  down 


204 


NAVAL  ORDNANCE 


the  bore  and  out  at  the  muzzle,  spinning  around  its  axis  100 
times  per  sec.  In  Fig.  1  (a)  and  {b)  is  shown,  respectively, 
a  projectile  before  and  after  firing  at  an  armor  plate;  the 
right-hand  figure  shows  the  effect  of  the  rifling  on  the  soft- 
copper  band. 

The  projectiles  now  commonly  used  in  naval  guns  are 
shown  in  Fig.  2,  of  which  (a)  is  the  armor-piercing  shell, 
(b)  the  common  shell,  and  (c)  shrapnel.  Both  armor-pierc- 
ing shell  and  common  shell  are  made  of  forged  and  tem- 
pered steel.  They  differ 
from  each  other  chiefly  in 
the  size  of  the  interior  cav- 
ity, which  carries  the  burst- 
ing charge,  and  in  the 
thickness  of  the  walls.  In 
order  that  they  shall  have 
the  same  weight  when 
filled,  the  common  shell  is 
considerably  longer  than 
the  armor  piercer. 

Armor-piercing  shells  are 
intended,  primarily,  to  pen- 
etrate the  heavy  armor  of 
battle  ships  and  armored 
cruisers.  It  is  very  desir- 
able that  they  should  burst 
after  getting  through;  but 
whether  or  not  they  can  be 
made  to  do  this  depends 
on  the  kind  of  explosive  with  which  they  are  loaded  (black 
powder,  guncotton,  lyddite  etc.)  and  on  the  nature  of  the 
fuse  that  is  used  to  explode  them.  Both  of  these  matters 
will  be  considered  later.  A  good  armor-piercing  shell  should 
penetrate  a  thickness  of  hard-faced  armor  equal  to  its  own 
caliber.  Thus  a  6-in.  shell  should  penetrate  G  in.  of  armor 
without  breaking  up. 

Common  shells  are  designed  to  penetrate  the  unarmored 
parts  o£  ships,  and  parts  protected  by  comparatively  thin 
armor.     As  they  carry  a  very  large  bursting  charge,  they 


Fig.  1 


NAVAL  ORDXAXCE 


205 


cannot  fail  to  be  very  destructive  to  the  interior  of  a  ship 
and  to  the  personnel  if  they  can  be  made  to  burst  inside. 
Here  again  the  question  of  the  bursting  charge  and  the 
fuse  comes  in,  but  this  difference  may  be  noted  between 
an  armor-piercing  and  a  common  shell;  that  the  former 
accomplishes  its  principal  purpose  if  it  penetrates  or  breaks 
up  the  enemy's  armor,  even  if  it  does  not  explode;  whereas 
the  latter  fails  of  its  principal  purpose  if  it  does  not  explode 
inside  the  enemy's  ship. 

Shrapnel  are  used  only  against  exposed  masses  of  men, 
whether  on  shore,  on 
the  deck  of  a  ship,  or 
in  boats.  This  class 
of  projectiles  is  al- 
ways fitted  with 
time  fuses,  set  to  ex- 
plode at  a  certain 
point  of  their  flight, 
the  idea  being  that 
they  will  explode 
above  and  in  front 
of  the  body  of  men 
against  whom  they 
are  fired.  As  a  re- 
sult of  the  explosion, 
not  only  the  frag- 
ments of  the  shell, 
but  all  the  small 
balls  with  which  the 
interior  is  filled,  are 
scattered  over  a  wide 
area. 

Capped  Projectiles. — The  capped  projectile,  types  of 
which  are  shown  in  Fig.  3,  is  a  development  of  the  last  few 
years,  and  has  increased  the  penetration,  other  things  being 
equal,  by  about  15%.  The  action  of  the  cap  has  not  been 
satisfactorily  explained,  but  the  following  indicates  the 
direction  in  which  the  explanation  is  to  be  found:  When 
a  projectile  strikes  an  armor  plate,  the  plate  springs  back 


206 


NAVAL  ORDNANCE 


more  or  less  under  the  blow,  and  at  the  same  time  a  con- 
siderable part  of  its  face  is  "dished"  a  little,  the  whole  of 
this  action  resulting  from  the  elasticity  of  the  plate  and  its 
supporting  structure.  This  spring  of  the  plate  is  unfavor- 
able to  penetration;  the  point  of  the  projectile  would  break 
through  the  face  of  the  plate  more  easily  if  the  latter  had 
no  spring  to  it.  When  a  capped  projectile  strikes  a  plate, 
the  cap  does  the  work  of  driving  back  the  plate  and  dishing 
it,  and  the  point,  when  it  breaks  its  way  through  the  cap. 


Fig.  3 

finds  the  plate  comparatively  rigid.  This  is  a  favorable 
condition  for  the  action  of  the  point,  and  it  gets  through 
more  easily  than  it  would  if  the  plate  were  yielding  while 
it  (the  point)  was  trying  to  get  in.  We  must,  of  cour.se, 
recognize  that  the  total  work  done  in  the  plate  is  no  greater 
in  one  case  than  in  the  other,  but  that  the  division  of  the 
work  into  two  parts — the  elasticity  being  exhausted  before 
penetration  begins — seems  to  make  the  penetration  greater 
than  it  would  otherwise  be.  All  armor-piercing  shells  are 
now  capped. 

FUSES 

Fuses    are    divided    into    two    general    classes — time   and 
percussion. 

The  time  fuse  is  one  that  can  be  so  arranged  as  to  cause 
the  explosion  of  a  shell  at  the  end  of  a  certain  interval  of 


A^4F.4L  ORDNANCE 


207 


time.  This  is  accomplished  by  means  of  a  column  of  slow- 
burning  composition  that  is  ignited  in  some  way  on  the 
firing  of  the  gun,  the  length  of  the  column  being  such  that 
it  will  bvirn  for  the  desired  interval  of 
time  before  communicating  flame  to 
the  bursting  charge.  The  length  of 
the  column  can  be  adjusted  for  the 
desired  interval  before  the  shell  is  fired. 
Time  fuses  are  used  in  the  Navy  for 
shrapnel  only,  these  being  the  only 
projectiles  that  are  exploded  before 
striking  the  target  at  which  they  are 
fired. 

A  percussion  fuse  carries  a  percus- 
sion cap  that  is  exploded  on  striking  a 
target,  provided  that  the  shell  meets  sufficient  resistance  to 
slow  it  down  materially.  The  cap  is  exploded  by  a  sharp- 
pointed  plunger,  which  drives  forwards  when  the  shell  is  sud- 
denly slowed  down  or  arrested.  It  is,  of  course,  very  impor- 
tant to  hold  the  plunger  securely  until  the  time  of  firing,  so 

that    it    cannot   pos- 


sibly strike  the  cap 
and  explode  it  by 
a  cc  i  d  e  n  t .  M  a  n  >- 
arrangements  have 
been  devised  for  this 
purpose;  and  it  is  the 
nature  of  this  device 
that,  to  a  great  ex- 
tent, determines  the 
individuality  of  the 
many  patented  fuses 
that  are  in  common 
use.  Two  characteristic  devices  are  shown  in  Figs.  1  and  2. 
In  the  Navy  percussion  fuse.  Fig.  1,  the  plunger  P  is  held  in 
place  by  a  brittle  wire  that  is  strong  enough  to  resist  any 
ordinary  shock  to  which  a  projectile  might  be  subjected  in 
handling,  even  if  dropped  from  a  considerable  height.  The 
shock  of  discharge  of  the  gun  is  sufficient  to  break  the  wire, 


Fig.  2 


208  NAVAL  ORDXANCE 

and  as  the  projectile  moves  forwards,  the  plunger  is  thrown 
to  the  rear  of  the  cavity  in  which  it  fits.  When  the  shell 
strikes,  the  plunger  flies  forwards  and  pierces  the  cap.  The 
flame  from  the  explosion  of  the  cap  flashes  through  several 
channels  (not  shown)  to  the  interior  of  the  shell,  where  it 
ignites  the  bursting  charge  and  explodes  the  shell. 

In  the  Driggs  fuse,  Fig.  2  (a),  the  plunger  is  held  in  place 
by  two  springs  c,  c\  that  are  thrown  outward  as  in  (6), 
when  the  shell  is  fired  from  the  gun,  by  the  centrifugal 
force  due  to  the  rotation  of  the  shell.  This  releases  the 
plunger  and  leaves  it  free  to  act.  This  principle  of  a  spring 
or  catch  holding  the  plunger  under  ordinary  circumstances, 
but  released  by  the  spinning  of  the  shell,  has  been  applied 
in  a  great  variety  of  ways,  some  of  them  extremely  ingenious. 

Base  Fuses. — All  fuses  are  now  used  in  the  base  of  the 
shell,  leaving  the  point  of  full  strength  for  penetration. 
This  makes  it  important  to  have  a  gas-tight  joint  where 
the  fuse  screws  in,  as  a  leak  of  gas  into  the  interior  of  the 
shell  will  cause  the  shell  to  explode  in  the  bore. 

Delayed-Action  Fuses. — A  delayed-action  fuse  is  one  in 
which  the  mechanism  is  so  arranged  that  the  explosion  of  the 
shell,  instead  of  taking  place  immediately  upon  impact  against 
armor,  is  delayed  until  the  shell  has  had  time  to  penetrate, 
thus  causing  the  explosion  to  take  place  inside  the  ship 
instead  of  outside.  Many  very  ingenious  fuses  of  this  kind 
have  been  devised,  but  their  mechanism,  being  somewhat 
complicated,  cannot  be  explained  here  for  lack  of  space. 

GUN  MOUNTS 

The  structure  on  which  a  gun  is  carried,  and  by  which  it 
is  controlled  in  pointing  and  firing,  is  called  a  mount,  or, 
sometimes,  a  carriage.  The  requirements  of  a  carriage  are 
that  it  shall  admit  of  easy  and  rapid  pointing,  both  in  azimuth 
and  in  elevation;  that  it  shall  lend  itself  to  maximum  rapidity 
of  fire;  that  it  shall  absorb  the  inevitable  recoil  of  the  gun 
without  undue  strain;  that  it  shall  have  sufficient  strength 
to  withstand  such  strains  as,  under  the  most  extreme  condi- 
tions, will  result  from  the  recoil;  and  that  it  shall  return  the 
gun   automatically  to    the  firing    position   (technically,  "to 


NAVAL  ORDNANCE  209 

battery")  immediately  after  the  recoil.  As  a  rule,  the  mount 
is  in  two  parts,  one  of  which  can  move  in  and  out  upon  the 
other.  The  gun  is  attached  to  the  movable  part,  the  top 
carriage,  and  this  top  carriage  recoils  with  the  gun.  In  the 
simplest  style  of  mount,  used  only  with  the  smallest  guns, 
the  top  carriage,  carrying  the  gun,  moves  laterally  around  a 
heavy  pivot  fitting  into  the  lower  part  of  the  mount,  but  no 
recoil  is  provided  for,  the  shock  of  firing  being  absorbed  by 
the  "give"  of  the  mount.  This  puts  a  great  strain  on  the 
mount  and  the  part  of  the  ship  to  which  it  is  secured,  and 
is  not  practicable  with  guns  larger  than  the  6-pdr. 

In  a  great  majority  of  the  mounts  now  in  use,  the  recoil 
is  absorbed  by  a  piston  moving  through  a  liquid  in  a  cylinder. 
This  liquid  is  usually  water,  to  which  a  certain  percentage 
of  glycerine  is  added  to  prevent  freezing.  The  piston  rod 
is  attached  to  the  top  carriage,  and  the  cylinder  to  the 
lower  carriage  (or  the  reverse).  To  admit  of  a  flow  of 
liquid  past  the  piston,  grooves  are  cut  along  the  interior 
surface  of  the  cylinder,  affording  channels  through  which 
the  liquid  makes  its  way  from  one  side  of  the  piston  to  the 
other  as  the  piston  is  forced  through.  Evidently,  the 
width  of  these  grooves  determines  the  freedom  with  which 
the  piston  can  move;  that  is  to  say,  the  freedom  of  recoil. 
As  it  is  desirable  that  the  recoil  should  be  very  free  at  first, 
and  checked  gradually,  the  grooves  are  made  wide  at  that 
part  of  their  length  which  corresponds  with  the  beginning  of 
motion,  and  are  gradually  "choked"  down  toward  the  oppo- 
site end.  The  length,  width,  and  depth  of  the  grooves  evi- 
dently determine  the  length  and  velocity  of  recoil,  and  these 
dimensions  are  carefully  calculated  for  each  class  of  gun. 

For  returning  the  gun  to  the  firing  position  after  recoil, 
heavy  spiral  springs  are  used  in  the  cylinders.  These  springs 
are  compressed  by  the  recoil  and  must,  of  course,  play  an 
important  part  in  checking  the  recoil,  their  resistance 
being  added  to  that  of  the  liquid.  As  soon  as  the  recoil  is 
arrested,  the  springs  run  the  gun  out  ready  for  another  fire. 

The  gun  is,  whenever  practicable,  secured  near  its  center 
of  gravity  to  the  top  carriage,  so  that  it  w^ll  be  balanced 
perfectly,  and  its  bearings  are  made  so  nearly  frictionless 


210  NAVAL  ORDNANCE 

that  very  little  power  is  needed  to  elevate  or  depress.  The 
little  power  required  is  furnished  by  a  beveled  gearing  in 
the  hands  of  the  pointer,  who,  with  his  eye  ranging  along 
the  sights,  endeavors  to  keep  the  gun  pointed  on  the  target 
in  spite  of  the  rolling  and  pitching  of  the  ship. 

The  lateral  training  is  done  by  another  set  of  gear-wheels, 
worked  by  another  gun  pointer,  who  also  is  provided  with 
a  sight,  and  whose  duty  it  is  to  keep  the  gun  trained  upon  that 
point  of  the  enemy's  length  at  which  he  is  told  to  aim. 
The  pointer  who  has  charge  of  the  elevation  controls  the 
firing  key  and  fires  the  gun;  his  object  should  be  to  keep 
his  sight  on  the  target  at  all  times.  This  is  called  continuous 
aim,  and  has  only  recently  been  made  possible  by  the  improve- 
ment in  gun  mounts  and  sights.  The  "importance  of  it  in 
the  case  of  a  single  shot  may  be  explained  as  follows:  There 
is  a  perceptible  interval  between  the  instant  when  the 
pointer  decides  to  fire  and  the  instant  when  the  projectile 
actually  leaves  the  muzzle  of  the  gun.  This  interval  for 
an  8-in.  gun  of  50  calibers  is  found  to  be,  roughly,  -^  sec. 
Suppose  the  ship  to  be  rolling  10  times  per  min.,  through 
6°  on  each  side  of  the  vertical.  The  muzzle  of  the  gun  will 
sweep  through  12'  of  arc  in  xV  sec,  and  this  at  a  range  of 
2,000  yd.  corresponds  to  an  error  in  height  on  the  target 
of  21  ft.  Thus,  if  the  pointer  decides  to  fire  at  a  given 
instant,  his  sights  being  exactly  on  the  point  of  the  target 
which  he  wishes  to  hit,  his  aim  may  be  thrown  off  by  21  ft. 
by  the  time  the  projectile  leaves  the  muzzle  of  the  gun, 
unless  he  continues  to  keep  the  sights  on  the  target  during 
the  actual  discharge  of  the  gun.  Where  a  string  of  shots 
is  to  be  fired,  the  advantage  of  continuous  aim  is  greatly 
increased.  Assuming  that  the  system  can  be  carried  out 
ideally,  and  assuming  also  that  the  lateral  aim  is  main- 
tained perfectly,  as  it  easily  can  be,  it  should  be  possible 
to  fire  as  rapidly  as  the  gun  can  be  loaded,  and  to  make  a 
hit  every  time. 

Turret  Mounts. — In  the  case  of  large  guns  mounted  in 
turrets,  the  lower  carriage  is  composed  of  heavy  slides 
bolted  to  the  turret  and  turning  with  it.  The  gun  rests 
in  a  cradle  that  moves  in  and  out  on  the  lower  carriare 


NAVAL  ORDNANCE  211 

exactly  as  in  the  mounts  for  lighter  guns.  The  elevation  is 
done  by  very  heavy  rams,  usually  hydraulic.  The  lateral 
training  of  the  turret  trains  the  guns  also.  A  vertical 
framework  in  the  rear  of  the  gun  furnishes  guide  rods  for 
an  ammunition  car,  which  runs  up  and  down  like  an  elevator 
bringing  ammunition  from  the  magazines  below  to  the 
loading  position  in  the  rear  of  the  guns.  A  rammer  worked 
by  hydraulic  or  electric  power,  and  installed  directly  in  the 
rear  of  the  gun,  pushes  the  projectile  and  the  powder  charge 
from  the  ammunition  car  into  the  gun.  The  rammer  is 
telescopic  in  its  working;  that  is  to  say,  when  not  in  use  it 
shortens  on  itself.  A  description  of  a  turret  mount  would 
demand  more  space  than  can  be  given  here;  the  attached 
illustration,  however,  gives  a  general  view  of  mount  for  the 
13-in.  gun  of  the  U.  S.  S.  "Oregon,"  and  by  referring  to  the 
accompanying  numbers  the  essential  parts  of  the  mechanism 
are  readily  identified. 

1,  gun;^,  saddle;  ^,  front  straps;  7,  rear  straps;  //.recoil 
cylinder;  13,  rear  bonnet;  IS,  stuffingbox  and  gland;  14, 
opening  for  pump  pressure  and  check-valve;  15,  pre.- sure 
side;  16,  reverse  side;  17,  spring  valve;  £0,  piston  rod,  h«.^d, 
and  nut;  21,  overflow  chamber;  S2,  connection  for  waste 
pipe;  S3,  lug  for  elevator  connecting-rod;  24,  slide;  S7,  turret 
girders;  S8,  deckings;  ;?5,  collar  for  pressure  pipe;  S^,  pivot 
bolts;  33,  elevator;  35,  elevator  connecting-rod;  36,  elevator 
valves;  37,  elevator  valve  rods  and  levers;  38,  elevator  pres- 
sure pipe;  39,  elevator  exhaust  pipe;  40,  hydraulic  rammer 
in  loading  position;  42,  hydraulic  rammer  brackets;  43. 
hydraulic  rammer  transom;  44,  hydraulic  rammer  trun- 
nions; 4o,  hydraulic  rammer  valves;  46,  hydraulic  rammer 
operating  lever;  47,  hydraulic  rammer  fulcrum  for  lever,  and 
guide  for  valve  stem;  48,  ammunition  car;  49,  ammunition 
car  motor  run  in;  51,  ammunition  car  motor  valves;  52, 
ammunition  car  motor  pressure  pipe;  53,  ammunition  car 
motor  exhaust  pipe;  54,  ammunition  car  guide  rails;  56, 
ammunition  car  bracket  and  sheave;  58,  pedestal  for 
central  column;  59,  central  column;  60,  water  section; 
61,  pressure  pipe;  62.  exhaust  pipe;  63,  platform;  64,  ladder 
to  turret;  65,  sights;  67,  rollers;  68,  roller  paths. 


212 


NAVAL  ORDNANCE 


SUOJ, 
-lOOJ 

aizzniv 


-*  ift      05  o -t  «  «  o -«•  o  00  ;o 

X3*.       cn;CQOior-  oac^r^xcc 


spnoosg 

-100  j[ 
'O01AJ3S) 
AIP'H3_Y 

aizzniv 


ooooogogggooooo 
00  =  0-.  OTTc:  0  =  00  —  —  o>a> 


sptinoj 
•aiiioafojj  JO  iqSia.vi 


i-"Mrceo:cin?cooooooo^o 


spunoj 
•japMoj 
ssaia5ioui>; 


spanoj 
'japMOj 
nMoag 


!  O  00  I 


qoai 
'jaqniBqo  jo  q-jgnai 


m  t-  ^  to  F-  o  e^  ai  t-;  o  o  o  o  •* 
p-'  •*■  in  -^  I-  ri  r-  tc  ci  ■*"  ■♦'  ^"  t-^  00 


qoni 


qoui 
'ajoaiomSnaTiBjoi 


jaaj^  'm3naT  lujox 


^^■>i^,-m-*-*t~'sa-i' 


^^  sc  >o  O  CO  >o  O  — ^  00  00 
o^"  r^  r-^  O  o  — '  o  cc  ='  ec  M 
-r  o  «o  o  ■«  35  ■«  t-  00  X  — 


■  X5  «  --O  00  —  —  >0 


suox  'jq3ia^ 


qoai  'iaqiiBO 


«-*-*-crf5in>nX5cto»«o;oxi 


.  ?  ?  ? 

O  irt  o 


'v_  3-  cr  cr  =•  cr  s-js  ^  ^  jC  js  o-  o* ; 
c  =  ='  =  .5  ='  =  a  d  a  3  a  a  a  ! 
«•^■*■^»ftlnlOX(©!©cC!OX^o^ 


NAVAL  ORDXAXCE 


213 


1 

c 

1 

BUOi 
-JOOJ 

aizznn 

6,932 

7,498 
8,011 
13,602 
13,864 
14,709 

13,864 
15,285 
27,204 
25,985 
46,246 
33,627 
40,350 

fs'?^:^ 

2.000  1 
2,000  / 

2,080 
2,150 
2,800 
2,000 

2,060 
2,000 
2,100 
2,800 
2,100 
2,800 
2,100 
2,300 

spnnoj 
'aipoafojjjOiqSiaji. 

f250 

250 
250 
250 
500 

500 

500 
500 
500 
850 
8.50 
1,100 
1,100 

o  ~ 

Is 

spnnod 
'japjAOj 

SS8I85lOinS 

3           i  i.  % 

sptinoj 

'WPAOJ 

uiioja 

105  to  115 
225  to  240 

425 
550 

qoni 
'jsqniBqo  jo  ^^3a^^ 

42.1 
42.1 
45.1 
45.1 
64.0 
.57.2 
57.2 

.57.2 
57.2 
75.6 
74.1 
91.9 
80.9 

qoai 
■SnxBta  JO  qiSaaq 

195.2 

195.2 
242.8 
282.8 
271.0 
247.3 
283.7 
247.3 
294.9 
313.4 
343.1 
388.1 
370.5 
370.5 

qoni 
'8Jog  JO  qjsuai  ibjox 

239.9 
2:i9.9 
290.5 
330.5 
335.0 
306.3 

343.8 
307.3 
354.9 
389.0 
419.2 
480.1 
454.5 
454.5 

188 J  'qjSnsT  iBjox 

21.5 

21.5 
25.4 
28.7 
28.6 
27  4 

27.4 
31.2 
33.3 
36.8 
41.8 
40.0 
40.0 

snox  'jqSiajv 

13.0 
13.1 
15.2 
180 
25.7 

25.1 

27.6 

33.4 

46.2 

52 

60.5 

60.5 

qoni  'Jsqil^O 

X  xxxxo  o  2222222 

Nature  of  Gun 

8-in.  b.  1.  r.,  mark  I.        . 

8-iii.  b.  1.  r.,  mark  II. 

81n.  b.  1.  r.,  mark  III,  of  35  cals. 

8-in.  b.  I.r.,  mark  III.,  of  40  cals. 

8-in.  b.  1.  r.,  mark  V.,  of  45  cals. 
10-in.  b.  1.  r.,  mark  I.,  of  30  cals. 
10-in.  b.  1.  r.,  mark  I.,  of  35  cals. 

10-in.  b.  1.  r.,  mark  II.,  of  30  cals. 

10-in.  b.  1.  r.,  mark  II.,  of  35  cals. 

10-in.  b.  1.  r.,  mark  111.,  of  40  cals. 

12in.  b.  1.  r.,  mark  I. 

12-in   b.  1.  r.,mark  III.,  of  40  cals. 

13-in.  b.  1.  r.,  mark  I. 

13-in.  b.  I.  r.,  mark  II.     . 

^2 


^ ".      I 


214  EXPLOSIVES 

EXPLOSIVES 

An  explosive  ma-\'  be  defined  as  a  substance  that,  existing 
normally  in  a  solid  or  liquid  state,  and  occupying,  in  that 
state,  a  comparatively  small  volume,  is  capable  of  being 
suddenly  converted  into  gas  with  very  great  increase  of 
volume;  or  if  it  is  prevented  from  expanding  freely,  then 
with  very  great  increase  of  pressure. 

There  are  great  differences  between  explosives  in  the 
suddenness  with  which  their  explosion  is  effected;  some 
substances,  like  nitroglycerine,  being  converted  into  gas 
almost  instantaneously,  while  others  require  an  appreciable 
time.  This  difference  is  of  very  great  importance  in  the 
application  of  explosives  to  military  purposes.  We  are 
accustomed  to  think  of  the  explosion  of  powder  in  a  gun 
as  taking  place  instantaneously.  The  time  occupied  is 
extremely  short,  but  it  is  many  times  as  long  as  that  required 
for  the  explosion  of  nitroglycerine.  To  understand  the 
difference,  we  must  recognize  the  fact  that  an  explosion  is, 
after  all,  only  a  case  of  combustion — a  case,  that  is  to  say, 
of  the  combination  of  certain  substances  with  oxygen. 
In  ordinary  cases  of  combustion,  as  of  burning,  the  sub- 
stance that  bums  (usually  some  form  of  carbon)  finds  the 
oxygen  for  its  combustion  in  the  air;  and  as  this  supply  is 
very  diffuse,  and  diluted  by  large  quantities  of  nitrogen, 
the  combustion  takes  place  slowly.  In  the  case  of  gun- 
powder, the  oxygen  for  the  combustion  of  the  carbon  exists 
in  a  concentrated  form  in  one  of  the  solid  ingredients  of 
the  powder,  where  it  is  in  intimate  contact  with  the  carbon 
and  other  substances  that  are  to  be  burned.  This  results 
in  an  enormous  increase  of  rapidity  in  the  combustion,  the 
gases  being  given  off  so  rapidly  as  to  constitute  an  explosion. 
In  gunpowder,  we  have  an  example  of  a  mechanical  mixture 
between  the  substances  that  are  to  be  oxidized  and  the 
substances  that  supply  the  oxygen  for  the  oxidation  (com- 
bustion). Evidently,  there  will  be  a  much  more  intimate  con- 
tact, and  an  even  more  sudden  combination,  if  we  associate 
the  oxygen  and  the  substance  with  which  it  is  to  combine 
in  a  single  substance.  Nitroglycerine  is  a  substance  of  this 
kind.     It  contains  carbon  and  nitrogen,  both  of  Vhich  are 


EXPLOSIVES  215 

oxidizable  substances,  and  it  also  contains  the  oxygen  neces- 
sary to  oxidize  them.  In  appearance  nitroglycerine  resem- 
bles a  heavy  oily  liquid.  If  this  liquid  receives  a  shock,  the 
original  arrangement  of  its  components  is  broken  up,  and  the 
oxygen  instantly  combines  with  the  carbon  and  nitrogen  to 
form  various  gases,  thus  producing  an  explosion  that  is  many 
times  as  violent  as  that  of  gunpowder,  because  many  times  as 
sudden.     Such  an  explosion  as  this  is  called  a  detonation. 

The  volume  of  the  gases  resulting  from  an  explosion  or 
detonation  is  many  times  that  of  the  solid  or  liquid  from 
which  they  are  derived,  but  their  volume  is  still  further 
increased  by  the  heat  that  is  liberated  by  the  combination 
of  the  various  parts.  Such  a  liberation  of  heat  always 
occurs  when  substances  combine  chemically  with  each 
other,  as,  for  example,  when  the  carbon  that  makes  up  a 
large  proportion  of  our  wood  and  coal  combines  with 
oxygen,  or  burns.  It  is  evident  that  a  detonating  explosive, 
like  nitroglycerine,  is  unfit  for  use  as  a  propellant,  that  is, 
for  propelling  a  projectile  from  a  gun,  because  the  suddenness 
and  violence  of  its  e.xplosion  would  burst  the  gun  before 
the  projectile  was  started  from  its  seat.  What  is  needed 
for  a  propellant  is  a  more  gradual  explosion,  the  force  of 
which  will  be  exerted  more  as  a  push  than  as  a  blow.  To 
illustrate  the  difference,  let  us  imagine  that  a  heavy  sphere 
of  iron  is  lying  on  a  smooth  table.  Strike  this  a  sharp  blow 
with  the  hand,  and  the  hand  will  be  bruised  while  the 
sphere  will  be  hardly  moved;  the  force  exerted  does  not 
have  time  to  overcome  the  inertia  of  the  sphere.  Place  the 
hand  against  the  sphere  and  push  it,  at  first  with  little 
pressure  then  with  much  more,  but  with,  upon  the  whole, 
no  greater  expenditure  of  force  than  was  contained  in  the 
blow.  The  sphere  will  be  moved  slowly  at  first,  then 
rapidly,  and  the  hand  will  not  be  bruised  at  all.  This  is 
the  difference  between  a  force  applied  suddenly  and  the 
same  force  applied  gradually;  the  first  resembles,  in  a  general 
way,  the  violence  of  nitroglycerine,  the  other,  the  (compara- 
tively) gradual  action  of  gunpowder. 

The  same  characteristic  that  makes  the  various  high 
explosives  unsuitable   for  use   as   propellants  makes   them 


216  EXPLOSIVES 

admirable  for  use  as  bursting  charges  in  shell,  since  here 
their  violence  is  exactly  what  is  needed,  provided  that  it 
is  possible  to  explode  them  at  the  right  moment.  Unfor- 
tunately, they  are  nearly  all  extremely  sensitive  to  shock 
and  friction,  which  makes  them  very  dangerous  to  handle 
and  to  store,  and  especially  dangerous  for  use  in  a  shell  that 
is  to  be  fired  from  a  gun,  because  of  the  possibility  of  their 
being  exploded  by  the  shock  of  discharge  of  the  gun.  This 
danger  is  much  less  with  some  explosives  than  with  others, 
and  the  whole  progress  of  development  along  this  line  has, 
for  many  years,  been  directed  toward  the  discovery  of 
explosives  that,  while  having  a  maximum  of  power,  will  be 
insensitive  to  ordinary  shock,  to  friction,  and  to  flame, 
but  capable  of  detonation  by  a  fuse  whose  action  can  be 
controlled  with  entire  certainty.  This  will  make  it  clear 
that  the  fuse  is  as  important  as  the  explosive  itself.  If  the 
fuse  is  liable  to  act  prematurely,  there  is  still  danger,  no 
matter  how  trustworthy  the  explosive  may  be.  As  nearly 
all  fuses  contain  fulminate  of  mercury,  which  is  extremely 
sensitive  to  shock,  the  problem  of  designing  a  fuse  that 
will  be  sure  to  act  when  the  shell  strikes,  and  not  at  any 
other  time,  is  a  difficult  one. 

Perhaps  the  best  known  of  the  high  explosives  is  nitro- 
glycerine, previously  referred  to;  it  is  extremely  sensitive, 
and  is  not  very  generally  used  in  liquid  form.  Dynamite  is 
nitroglycerine  absorbed  in  a  soft  and  spongy  sand  called 
Kieselguhr;  in  this  shape  it  is  much  less  sensitive  to  shock, 
and  may  be  handled  and  transported  with  a  reasonable 
degree  of  safety.  It  is  much  too  sensitive,  however,  for 
military  purposes,  and  its  use  is  limited  to  blasting. 
Dynamite  No.  2,  Lithofracteur,  and  carhodynamite  are  modi- 
fications of  ordinary  dynamite,  and  contain  nitroglycerine 
associated  with  some  substance  that  is  supposed  to  render 
it  safe  in  handling  and  transportation. 

Guncotton,  formed  by  treating  ordinary  cotton  with  nitric 
acid,  is  in  many  respects  the  most  convenient  of  the  high 
explosives.  When  dry  it  is  very  sensitive,  but  when  wet  (with 
from  15%  to  30%  of  water)  it  is  insensitive  to  all  ordinary 
shocks,  but  may  be  caused  to  detonate  by  detonating  dry 


EXPLOSIVES  217 

guncotton  in  contact  with  it.  The  dry  cotton  can  be  detona- 
ted in  a  number  of  ways,  but  the  surest  and  most  convenient 
way  is  by  a  fuse  of  fulminate  of  mercury.  Guncotton  is  com- 
monly used  for  the  explosive  charge  in  torpedoes,  the  bulk  of 
the  charge  being  wet  cotton,  while  the  fuse  is  made  up  of  dry 
cotton  with  an  exploder  of  fulminate.  Guncotton  is  some- 
times used  in  this  way  as  a  bursting  charge  for  shells. 

Blasting  gelatine  is  a  compound  of  guncotton  and  nitro- 
glycerine, in  which,  singularly  enough,  the  qualities  of  both 
ingredients  are  so  far  modified  that  the  resulting  compound 
while  retaining  nearly  all  the  explosive  power  of  its  two 
constituents,  is  made  less  sensitive  than  either.  It  is 
probably  the  safest  of  the  high  explosives,  with  the  excep- 
tion of  wet  guncotton.  Rackarock  is  a  mixture  of  potassium 
chlorate  and  mono-nitrobenzene,  the  latter  being  an  easily 
oxidizable  form  of  carbon,  and  the  former  a  substance  rich  in 
oxygen.     HellhoTfiie  belongs  to  the  same  class  of  explosives. 

Fulminate  of  mercury,  which  has  already  been  mentioned, 
is  one  of  the  most  sensitive  and  violent  explosives  known, 
and  therefore  one  of  the  most  dangerous.  It  is,  in  fact, 
never  handled  except  in  verv'  small  quantities.  It  is,  how- 
ever, almost  indispensable  in  work  with  other  explosives, 
because  the  shock  resulting  from  its  detonation  has  some 
peculiar  characteristic,  not  fully  understood,  by  reason  of 
which  it  can  detonate  any  high  explosive  with  which  it  is 
in  contact.  Moreover,  the  flame  from  its  detonation  ignites 
(and  so  explodes)  gunpowder.  It  is  this  substance  that  is 
used  in  percussion  caps  and  in  the  cartridges  of  muskets 
and  revolvers;  it  is  also  used  in  almost  all  fuses  for  exploding 
large  shells,  when  extreme  care  must  be  taken  to  place  the 
fulminate  in  such  a  way  that  it  cannot  be  set  ofT  by  the 
shock  of  firing  the  gun.  This  is  not  as  difficult  as  the  same 
problem  is  when  connected  with  a  large  quantity  of  explosive, 
such  as  that  which  must  be  used  to  fill  the  shell.  If  the  shell 
were  filled  with  fulminate,  nothing  could  prevent  its  instanta- 
neous detonation  in  firing  the  gun,  and  as  a  result  the  gun 
would  be  blown  into  fragm.ents.  The  few  grains  of  fulminate 
used  in  detonators  can  be  disposed  of  in  such  a  way  that  it 
will  not  feel  the  shock  with  violence  enough  to  explode. 


218  EXPLOSIVES 

Among  the  most  common  of  the  high  explosives  in  use  for 
military  and  other  purposes  are  picric  acid,  and  the  various 
derivatives  of  this  acid  known  as  picrates.  These  sub- 
stances are  all  high  explosives,  and  many  of  them  are  so 
extremely  sensitive  that  they  cannot  be  used  for  military 
purposes.  Others  are  so  little  sensitiva  that  a  very  large 
charge  of  fulminate  is  required  to  detonate  them.  The  well- 
known  English  explosive  lyddite  is  picric  acid,  and  melinite, 
the  French  explosive,  is  derived  from  the  same  acid.  Shimose 
powder,  used  by  the  Japanese  with  great  effect  in  their  war 
with  Russia,  is  known  to  be  one  of  the  many  picrates. 

One  of  the  dangers  in  connection  with  picric  acid  arises 
from  the  fact  that  this  substance,  when  brought  in  contact 
with  iron  or  steel,  forms  the  picrate  of  iron,  which  is  almost 
as  sensitive  to  shock  and  friction  as  is  the  fulminate  of 
mercury.  It  is  therefore  necessary  to  coat  the  inside  of 
the  shells  with  lacquer  or  asphaltum,  and  to  be  very  careful 
that  the  acid  does  not  at  any  stage  of  preparation  or  handling 
come  in  contact  with  bare  iron. 

Gunpowder. — Ordinary  gunpowder  (black  gunpowder,  as 
it  is  now  called)  was  invented  some  6  centuries  ago,  and, 
strangely  enough,  remains  today  practically  unchanged  in 
composition,  although  variations  have  been  introduced 
from  time  to  time  in  the  proportion  of  the  ingredients,  and 
imporliant  variations  in  the  size  and  shape  of  the  grains. 
It  is  a  mixture  of  charcoal,  sulphur,  and  potassium  nitrate 
(commonly  called  saltpeter),  in  the  following  proportions: 
charcoal,  15%;  sulphur,  10%;  potassium  nitrate,  75%. 
Here  we  have  an  easily  oxidizable  substance,  charcoal 
(carbon),  and  a  substance  rich  in  oxygen,  potassium  nitrate. 
Broadly  speaking,  the  explosion  consists  in  the  production 
from  these  solid  substances  of  three  highly  heated  gases — 
nitrogen,  carbon-monoxide,  and  carbon-dioxide.  The  first 
of  these  exists  originally  in  the  potassium  nitrate,  where  it 
is  combined  with  the  oxygen.  When  the  nitrate  breaks 
up,  the  nitrogen  is  left  free  (as  a  gas),  and  the  oxygen  com- 
bines with  the  carbon  to  form  the  two  other  gases  that  have 
been  named.  The  sulphur  assists  in  the  various  chemical 
changes,  but  does  not  itself  form  a  gas.     It  appears  at  the 


EXPLOSIVES  219 

end  of  the  explosion  in  combination  with  the  potassium, 
forming  certain  solid  products  which  are  responsible  for  the 
smoke  and  the  deposit  in  the  bore,  both  of  which  are  objec- 
tionable features. 

For  many  years,  chemists  and  artillerists  have  been  in 
search  of  a  powder  whose  explosion  would  give  only  gaseous 
products.  There  were  many  advantages  to  be  anticipated 
from  such  a  powder.  It  would  be  more  powerful,  because 
all  its  energy  would  go  into  the  gas  that  propels  the  pro- 
jectile. It  would  be  smokeless,  because  the  smoke  of  black 
powder  is  due  to  solid  particles.  And  it  would  leave  no 
residue  to  foul  the  bore  of  the  gun.  In  all  this,  there  was 
reason  enough  for  seeking  a  new  explosive;  but  it  is  only 
within  quite  recent  years  that  it  has  been  regarded  as  an 
absolute  necessity.  With  the  introduction  of  rapid-firing 
guns  into  the  Navy,  it  became  necessary  to  have  a  powder 
giving  little  or  no  smoke,  if  these  guns  were  to  be  of  any  use 
for  the  objects  for  which  they  were  intended.  For  instance, 
in  repelling  the  attack  of  torpedo  boats,  the  use  of  black 
powder  would  entirely  defeat  the  purpose  of  the  guns,  as 
after  the  first  few  shots  the  cloud  of  smoke  would  com- 
pletely obscure  the  whereabouts  of  the  attacking  force  and 
render  the  guns  useless.  It  would,  in  fact,  play  directly 
into  the  hands  of  the  enemy  by  creating  a  curtain  behind 
which  they  could  push  home  their  attack  with  impunity. 

The  fact  that  the  smoke  given  by  black  -powder  is  due 
entirely  to  the  solid  products  resulting  from  the  combinations 
formed  by  the  potassium  of  the  potassium  nitrate,  after 
that  substance  has  given  up  its  oxygen  for  the  combustion 
of  the  charcoal,  naturally  suggested  the  idea  of  using  some 
nitrate  that  would  give  up  its  oxygen  in  the  same  way,  bi.t 
whose  further  compounds  would  be  gaseous.  Ammonium 
nitrate  is  a  substance  of  this  kind,  but  it  has  the  faculty  of 
absorbing  water  from  the  atmosphere  so  rapidly  that  it 
is  totally  unsuited  for  use  in  gunpowder.  It  has,  neverthe- 
less, been  the  basis  of  many  formulas  for  smokeless  powder, 
but  none  of  these  have  been  successful. 

About  1890,  there  was  brought  out  in  Germany  a  powder 
that,  from  its  peculiar  color,  came  to  be  known  as  brown  ox 


220  EXPLOSIVES 

cocoa  powder.  The  composition  of  this  was  kept  secret,  but 
analysis  showed  it  to  contain  a  much  smaller  proportion  of 
sulphur  than  black  powder,  and  a  larger  proportion  of  salt- 
peter and  of  moisture.  These  peculiarities,  however,  were 
not  sufficient  to  account  for  its  superiority  over  black 
powder.  Yet  this  superiority  was  very  marked.  It  gave  a 
higher  velocity  to  the  projectile,  with  much  less  strain  on 
the  gun,  and  the  smoke  was  notably  less  than  with  black 
powder.  The  secret  of  its  manufacture  was  closely  guarded, 
but  chemists  recognized  the  fact  that  this  secret  lay  in  the 
nature  of  the  charcoal  used,  and  that  this  charcoal  was  not 
as  fully  charred  as  that  which  was  used  for  black  powder. 
Starting  from  this  point,  several  manufacturers  developed^ 
cocoa  powders  that  equalled,  and  in  some  cases  exceeded, 
the  original  German  article.  It  is  now  known  that  the 
original  powder  was  made  from  straw  that  was  charred  by 
superheated  steam  which  did  not  reduce  it  to  pure  carbon, 
but  left  much  of  the  natural  structure  of  the  straw.  This 
partially  burned  straw  retained  oxygen,  hydrogen,  and 
other  substances  in  proportions  that  proved  favorable  to 
the  performance  of  the  powder. 

Cocoa  powder  entirely  drove  out  black  powder  for  large 
guns.  Although  a  distinct  reduction  was  made  in  the 
amount  of  smoke,  in  addition  to  improvements  in  other 
respects,  it  still  left  much  to  be  desired,  and  the  search 
for  a  really  smokeless  powder  was  continued. 

It  was  natural  that  attention  should  be  turned  to  the  high 
explosives,  since  all  the  products  of  these  explosives  are 
gases;  and  shortly  after  the  discovery  of  nitroglycerine  and 
nitrocellulose  (guncotton),  near  the  middle  of  the  19th 
century,  efforts  were  made  to  temper  the  violence  of  these 
explosives  sufficiently  to  make  them  suitable  for  use  as 
propellants.  Guncotton  was  much  more  promising  for  this 
purpose  than  nitroglycerine,  and  many  promising  results 
were  obtained  by  the  early  experimenters  with  it,  some  of 
whom  wrapped  threads  of  the  cotton  spirally  around  wooden 
or  other  cores,  while  others  reduced  the  cotton  to  a  powder 
and  mixed  with  it  certain  inflammable  but  non-explosive 
substances,  hoping  by  this  means  to  tame  and  control  the 


EXPLOSIVES  221 

burning  of  the  mixture.  These  mixtures  frequently  gave 
good  results;  but  they  were  unreliable  and  occasionally 
detonated  with  destructive  violence.  The  most  important 
step  in  advance  came  with  the  discovery  that  certain  sub- 
stances would  entirely  dissolve  guncotton,  completely 
destroying  the  cellular  structure  that  makes  up  its  fibers, 
and  reducing  it  to  a  gelatinous  mass  that,  when  allowed  to 
set,  takes  on  a  hard,  horny,  semitranslucent  character, 
such  as  is  familiarly  seen  in  celluloid.  Any  substance 
existing  in  this  form  is  called  a  colloid.  It  was  found  that 
in  the  colloid  form,  nitrocellulose  burned  rapidly,  but  with- 
out any  disposition  to  detonate,  and  that  its  burning  could 
be  as  perfectly  controlled  as  that  of  black  or  brown  gun- 
powder. Moreover,  it  lost  nothing  of  its  power,  since  its 
chemical  composition  remained  unchanged.  Thus  the  great 
problem  of  a  smokeless  powder  was  solved.  Among  the 
substances  that  have  the  power  to  dissolve  nitrocellulose, 
one  of  the  most  convenient  is  acetone,  an  aromatic  liquid 
resembling  alcohol.  Another  convenient  solvent  is  a  mixture 
of  ether  and  alcohol. 

The  nitrocellulose  having  been  dissolved  in  either  of  the 
above  solvents,  the  excess  of  the  solvent  is  removed  as  far 
as  possible  by  compression  and  evaporation,  but  a  con- 
siderable quantity  remains  in  the  powder  after  it  is  fully 
dried  and  gives  the  characteristic  odor  that  is  always  asso- 
ciated with  smokeless  powder. 

The  colloid  is  pressed  into  grains  of  the  desired  size  and 
shape,  after  which  it  is  dried.  It  is  then  ready  for  use. 
The  smokeless  powders  now  used  by  the  United  States, 
France,  and  Russia  are  produced  as  just  described;  that  is 
to  say,  they  are  nitrocellulose  powders  pure  and  simple. 

There  is  a  class  of  smokeless  powders  that  are  a  combina- 
tion of  nitrocellulose  with  nitroclygerine.  As  these  are 
both  violent  explosives,  it  is  rather  surprising  to  find  that 
mixing  them  produces  a  substance  whose  action  can  be 
perfectly  controlled;  a  substance,  in  short,  that  makes  an 
almost  ideal  smokeless  powder.  The  explanation  is  that 
the  nitroglycerine  acts  as  a  solvent  for  the  nitrocellulose, 
dissolving  it  as  perfectly  as   does  acetone,   and  forming  a 


222  EXPLOSIVES 

perfect  colloid.  Po-.vders  of  this  class  are  distinguished 
from  those  that  contain  nitrocellulose  only  by  referring  to 
them  as  nitroglycerine  powders;  but  it  must  be  remembered 
that  only  a  small  percentage  of  their  composition  is  really 
nitroglycerine.  The  well-known  English  powder  cordite  is 
of  this  class.  It  is  very  effective  as  a  propellant,  giving 
considerably  better  results  than  the  nitrocellulose  powders, 
but  it  develops  so  much  heat  in  burning  that  it  wears  away 
the  bore  of  the  gun  very  rapidly,  by  what  is  called  erosion. 
This  makes  it  less  satisfactory,  on  the  whole,  than  the  nitro- 
cellulose powders,  and  there  is  talk  among  English  artillerists 
of  substituting  one  of  these  for  the  cordite  at  present  in  use. 
Granulation  of  Powder. — With  any  composition  of  powder, 
whether  black,  brown,  or  smokeless,  the  size  and  shape  of 
the  grains  have  an  important  effect  on  the  action  of  the 
powder  in  the  gun.  Broadly  speaking,  a  small  grain  is 
favorable  to  rapid  combustion,  and  a  large  grain  to  slower 
and  more  gradual  burning.  A  small  granulation  is  adapted 
to  a  small  gun,  and  a  large  granulation  to  a  large  gun.  There 
are,  however,  many  other  considerations  that  enter  into 
the  problems  of  the  most  suitable  granulation  for  a  given 
gun.  When  the  powder  is  ignited,  it  burns  slowly  at  first, 
developing  a  pressure  that,  while  still  low,  starts  the  pro- 
jectile moving  down  the  bore.  This  motion  o*f  the  projectile 
increases  the  volume  in  which  the  gases  can  expand,  and  so 
would  lower  the  pressure  if  it  were  not  that  more  and  more 
gas  is  given  off,  so  that  the  pressure  is  not  only  maintained 
but  is  rapidly  increased  for  a  time;  after  which,  the  powder 
being  nearly  or  quite  consumed  and  the  space  continuing 
to  increase  very  rapidly,  as  the  projectile  is  driven  toward 
the  muzzle,  the  pressure  falls  off  almost  as  rapidly  as  it  at 
first  increased.  In  a  powder  that  burns  too  rapidly  for  the 
particular  gun  in  which  it  is  used,  the  pressure  rises  suddenly 
to  a  maximum,  which  perhaps  puts  a  dangerous  strain  on 
the  gun,  then  falls  off  so  quickly  that  it  communicates 
only  a  low  velocity  to  the  projectile.  An  ideal  powder  will 
give  a  low  maximum  pressure,  but  will  sustain  this  pressure 
well  down  the  bore  toward  the  muzzle  of  the  gun.  To  do 
this  we  need  what  is  called  a  progressive  powder,  or  one,  that 


EXPLOSIVES 


225 


224  TORPEDOES 

will  bum  slowly  at  first,  then  more  and  more  rapidly, 
keeping  up  the  pressure  behind  the  projectile  until  it  actu- 
ally leaves  the  gun.  For  this  purpose,  we  must  have  our 
grain  of  such  a  shape  that,  as  it  bums,  the  burning  surface 
will  increase.  Evidently  this  cannot  happen  with  any 
grain  that  bums  entirely  from  the  outside,  as  the  grain 
would  grow  steadily  smaller  and  the  surface  would  be 
reduced.  If  the  grain  is  pierced  with  holes  that  allow  it 
to  bum  from  the  inside  outwards,  as  well  as  from  the  outside 
inwards,  we  will  have  a  constantly  increasing  burning  surface 
and  therefore  a  progressive  powder.  This  is  the  object  of  the 
holes  with  which  many  forms  of  powder  grains  are  pierced. 
Such  a  grain,  if  having  one  hole  only,  is  called  single  perfo- 
rated or  tubular;  if  having  several  holes,  multiperf orated. 
Many  powders  are  made  in  solid  flat  strips  or  in  sticks. 

Various  forms  of  granulation  are  shown  in  the  figure,  page 
223,  each  form  being  designated  by  a  number,  as  follows: 
2,  13-in.  smokeless;  S,  flake  musket;  4,  8-in.  35  cal.  smoke- 
less; 5,  6-pdr.  smokeless;  6,  4-in.  50  cal.  smokeless;  7,  5-in. 
40  cal.  smokeless;  8,  black  musket;  9,  black  cannon;  10, 
black  hexagonal;  11,  black  Schagticoke  rifle;  12,  brown 
prismatic;  IS,  7-in.  45  cal.  strip,  experimental  smokeless; 
14,  8-in,  35  cal.  stick,  multiperforated  smokeless;  15,  12-in. 
40  cal.  single-perforated  smokeless;  16,  sphere  hexagonal 
smokeless. 

TORPEDOES 

The  torpedoes  of  the  present  day  are  all  automobile;  that 
is,  they  carry  in  themselves  their  own  motive  power.  In 
the  Whitehead  torpedo,  which  is  in  almost  universal  use,  this 
power  is  supplied  by  an  engine  run  by  compressed  air,  the 
air  being  stored  in  a  reservoir  that  occupies  considerably 
more  than  half  the  total  volume  of  the  torpedo.  Fig.  1 
shows  a  Whitehead  torpedo  in  section.  Reference  to  this 
figure  will  make  the  following  description  clear  so  far  as  the 
general  principles  of  its  mechanism  are  concerned.  A 
description  of  the  details  would  call  for  many  times  the 
«pace  that  can  be  given  to  it  here. 


TORPEDOES 


225 


War  Head. — The  bursting  charge 
of  high  explosive  (usually  guncot- 
ton)  is  contained  in  the  war  head  H, 
and  is  exploded,  in  case  the  torpedo 
strikes  a  solid  object,  by  the  action 
of  the  fuse,  which,  as  will  be  seen, 
projects  beyond  the  head.  A  plun- 
ger in  this  fuse  is  driven  in,  on  stri- 
king, and  pierces  a  percussion  cap 
containing  fulminate  of  mercury. 
The  explosion  of  this  cap  detonates 
the  high  explosive  in  the  war  head 
with  tremendous  force;  a  force 
amply  sufficient  to  blow  a  hole  in 
the  plating  of  any  ship,  and  also,  in 
most  cases,  to  explode  the  magazines 
of  the  ship  herself.  The  bursting 
charge,  in  the  latest  type  of  torpe- 
does, is  132  lb. 

Exercise  Head. — In  firing  the  tor- 
pedo for  drill,  an  exercise  head  is  sub- 
stituted for  the  war  head.  This 
exercise  head  is  of  the  same  dimen- 
sions and  weight  as  the  war  head,  but 
contains  no  explosive.  It  is  some- 
times made  of  very  thin  and  soft 
metal  so  that  it  collapses  on  stri- 
king, thus  proving  that  a  hit  has 
been  made. 

Air  Flask. — Immediately  abaft 
the  head  is  the  air  flask  B,  which  is 
charged  with  air  under  a  pressure  of 
more  than  2,000  lb.  to  the  square 
inch.  In  the  figure,  this  air  flask  has 
been  omitted  for  lack  of  space;  it 
is  equal  in  length  to  distanjce  from 
point  X  to  tail  of  torpedo.  In  bat- 
tle, the  flask  is  always  kept  charged, 
and  so  perfect  are  the  fittings  of  the 


226 


TORPEDOES 


valves  communicating  with  it  that  the  leakage  is  nardly  per- 
ceptible. Sufficient  air  is  carried  for  a  run  of  2  mi.,  and  it 
is  required  that  the  first  1,200  yd.  of  this  distance  shall  be 
made  at  a  speed  of  35  kn. 

Immersion  Chamber. — The  compartment  C  next  abaft  the 
air  flask  is  the  immersion  chamber,  containing  the  mecha- 
nism called  the  hydrostatic  piston,  by  means  of  which  the 
torpedo  is  made  to  run  at  any  desired  depth  below  the  sur- 
face of  the  water.  The  details  of  this  mechanism  are  com- 
plicated, but  its  general  principle  is  perfectly  simple.     The 


Wa/trPrtssure 


hi>/fr/,^AfSu/Mta^ 


FlO. 


object  is  to  steer  the  torpedo  down  if  it  rises  too  high,  and 
to  steer  it  up  if  it  sinks  too  low.  The  hydrostatic  piston 
is  actuated  by  two,  forces  that  oppose  each  other;  one  of 
these  is  a  spring,  the  tension  of  which  can  be  regulated  by 
screwing  up  a  nut;  the  other  is  the  pressure  of  the  water, 
which,  of  course,  varies  with  the  depth.  The  piston  is 
connected  by  a  series  of  levers  with  a  horizontal  rudder  at 
the  tail  of  the  torpedo,  so  that  as  the  piston  moves  back- 
wards or  forwards  it  cants  the  rudder  up  or  down,  and  so 
steers  the  torpedo  up  or  down.  In  Fig.  2  (which  is  diagram- 
matic merely)  o  is  a  water-tight  bulkhead  separating  the 


TORPEDOES  227 

immersion  chamber  from  the  adjoining  (engine  room)  com- 
partment. (See  also, Fig.  1.)  The  immersion  chamber  is 
absolutely  water-tight,  but  the  engine-room  compartment 
is  open  to  the  sea.  Thus  the  water-pressure  is  felt  on  one 
side  of  the  bulkhead  a,  but  not  on  the  other  side.  A  round 
hole  is  cut  in  the  bulkhead  and  covered  by  a  flexible  rubber 
diaphragm.  Inside  this  immersion  chamber,  a  piston 
moving  in  a  guide  tube  is  held  against  the  rubber  diaphragm 
by  a  spring,  which  opposes  its  own  tension  to  the  pressure 
of  the  water  on  the  other  side  of  the  diaphragm.  If  the 
water  pressure  exceeds  the  tension  of  the  spring,  the  dia- 
phragm is  buckled  in  slightly,  compressing  the  spring  and 
forcing  back  the  piston.  If,  on  the  other  hand,  the  water 
pressure  is  less  than  the  tension  of  the  spring,  the  spring 
extends  itself  and  forces  the  piston  the  other  way,  buckling 
the  rubber  diaphragm  outwards  into  the  engine  compartment. 

Attached  to  the  piston,  and  moving  with  it,  is  one  end 
of  a  rod  g,  pivoted  at  e  and  connected  through  a  system  of 
levers  with  the  horizontal  rudder  at  the  tail  of  the  torpedo. 
If  this  rudder  is  canted  upwards,  it  steers  the  torpedo  toward 
the  surface;  if  canted  downwards,  it  steers  the  torpedo  down. 

By  screwing  up  a  nut  (not  shown  in  the  diagram),  the 
tension  of  the  spring  can  be  varied  according  to  the  depth 
at  which  it  is  desired  to  have  the  torpedo  run.  Suppose 
that  it  is  desired  to  have  it  run  at  10  ft.  below  the  surface 
so  that  it  will  strike  the  enemy's  ship  10  ft.  below  the  water- 
line.  The  adjusting  nut  of  the  spring  is  then  screwed  to 
a  mark  (previously  determined  by  experiment)  that  we  know 
will  make  the  tension  of  the  spring  exactly  equal  to  the 
water  pressure  10  ft.  below  the  surface.  Suppose  that  after 
the  torpedo  is  launched,  it  starts  off  15  ft.  below  the  surface. 
The  water  pressure  on  the  diaphragm  is  too  strong  for  the 
spring,  the  spring  yields,  the  piston  moves  forwards,  the 
rudder  is  canted  upwards  and  steers  the  torpedo  toward 
the  surface.  Perhaps  it  now  rises  a  little  too  high,  allowing 
the  spring  to  overcome  the  water  pressure  and  force  the 
piston  back;  this  cants  the  rudder  the  other  way  and  steers 
the  torpedo  downwards  a  little.  After  a  few  variations 
up  and  down,  each  one  less  marked  than  the  one  preceding. 


228  TORPEDOES 

the  torpedo  steadies  itself  at  the  proper  depth  and  keeps 
this  throughout  the  run.  The  actual  working  of  the  rudder 
is  accomplished  by  a  small  steering  engine,  the  valve  of 
which  is  controlled  by  the  rod  from  the  hydrostatic  piston. 
This,  of  course,  does  not  change  the  fact  that  it  is  the  hydro- 
static piston  that  governs  the  steering. 

Main  Engine. — The  engine  is  in  the  compartment  D  next 
abaft  the  immersion  chamber,  which  compartment,  as 
already  explained,  is  open  to  the  sea.  The  engine  is  con- 
nected with  the  air  flask  by  a  pipe  (not  shown  in  figure)  in 
which  are  two  valves.  One  of  these,  the  stop  valve,  is 
opened  just  before  the  torpedo  is  fired,  the  other  opens 
automatically  as  the  torpedo  passes  out  of  the  tube,  being 
governed  by  a  lever  that  projects  above  the  torpedo  in  such 
a  position  that  it  strikes  against  a  projection  on  the  tube 
and  is  thrown  back,  opening  the  valve.  Even  this,  how- 
ever, does  not  start  the  engine.  If  it  did,  the  propellers 
•would  begin  to  spin  with  great  violence  (technically  to 
race)  before  the  torpedo  entered  the  water.  Another  lever 
must  be  tripped  before  the  air  can  reach  the  valve  chest 
of  the  engine;  this  is  a  small  lever  so  placed  that  as  the 
torpedo  enters  the  water,  the  resistance  of  the  water  throws 
down  the  lever  and  allows  the  engines  to  start. 

Propellers. — To  insure  the  straight  running  of  the  torpedo, 
two  propellers  p  p\  are  used,  placed  "tandem,"  one  being 
right-handed  and  the  other  left-handed.  The  after  one  is 
keyed  to  the  shaft  and  turns  with  it.  The  forward  one  is 
keyed  to  a  sleeve  on  the  shaft  and  worked  from  the  shaft 
by  a  set  of  beveled  gearing.  The  necessity  for  two  pro- 
pellers turning  in  opposite  directions  arises  from  the  ten- 
dency that  a  propeller  always  has  to  throw  the  stern  to  one 
side  or  the  other,  according  as  it  is  right-  or  left-handed. 

Steering. — It  will  be  noted  that  the  torpedo,  as  thus  far 
described,  has  no  arrangement  for  steering  to  right  or  left. 
Until  quite  recently  no  such  arrangement  has  been  considered 
necessary  or  practicable.  It  has  been  assumed  that  the 
torpedo  will  follow  the  course  in  which  it  is  launched,  and 
great  care  is  taken  to  insure  this  by  making  the  body  per- 
fectly symmetrical  and  balancing  the  weights  as  exactly  as 


TORPEDOES  229 

possible.  When  a  torpedo  is  completed,  it  is  tested  as  to 
accuracy  in  running,  and  any  defect  is  corrected  by  moving 
a  small  vertical  vane  on  the  tail-piece,  which,  once  adjusted, 
is  clamped  securely  and  never  thereafter  disturbed.  It  is 
well  known  that,  as  a  matter  of  fact,  torpedoes,  however 
carefully  tested  and  adjusted,  behave  very  erratically  in 
service.  Cases  have  been  known  in  which,  after  running 
a  certain  distance,  they  have  turned  and  run  straight  back 
toward  the  ship  from  which  they  were  fired. 

The  Obry  Gear. — A  very  ingenious  device,  known  as  the 
Obry  gear,  has  recently  been  introduced,  which  can  either 
be  used  to  keep  the  torpedo  true  to  the  course  on  which  it 
is  launched,  or  can  cause  it  to  change  its  course  after  running 

a  certain  distance  and  take  up  a  . 

wholly    different    course,    decided    I  ^^ 

upon  just  before  firing.     Supposa    '^  -^ — 

that  a  torpedo  boat  having  two 

tubes,   one   on  each  broadside,  is  \ 

running  toward  a  battle  ship  that  ^  J 

she  proposes  to  attack.     Under  i  ^' 

ordinary  circumstances,  she  would  ^^  /' 

have  to  change  her  course  before  ^s^  / 

firing,  in  order  to  bring  one  tube  to 

bear,  and  the  chance  of  making  a 

hit  while  changing  course  would  be  F       "^ 

very  slight.      If  the  torpedoes  are 

fitted  with  the  Obry  gear,  she  can  turn  both  tubes  off  on  the 

bow  or  broadside  and  launch  both  torpedoes  at  once,  the  Obry 

gear  having  been  set  in  such  a  way  that  each  torpedo,  after 

running  50  yd.,  for  example,  will   turn   and  head  directly 

toward  the  enemy,  as  shown  in  Fig.  3. 

The  essential  part  of  the  Obry  gear  is  a  gyroscope,  or 
flywheel,  that  is  set  spinning  at  a  very  high  velocity.  The 
principle  of  the  gyroscope  is  this:  A  fly  wheel  which  is  spin- 
ning in  a  given  plane  has  a  very  strong  tendency  to  con- 
tinue spinning  in  that  plane,  and  to  resist  any  effort  to  turn 
it  into  another  plane. 

In  Fig.  4  is  shown  a  view  of  the  Obr\'  gear,  a  being  the 
gyroscope  and  b  the  sector  containing  the  actuating  spring. 


230 


TORPEDOES 


The  axis  of  the  gyroscopic  wheel  is  placed  in  a  fore-and-aft 
direction  in  the  torpedo,  and  no  matter  how  the  torpedo 
turns  to  right  or  left  the  spinning  gyroscope  by  its  inherent 
directive  force  will  cause  the  torpedo  to  turn  back  to  its 
original  direction.  In  torpedoes  using  the  Obry  gear, 
vertical  rudders  are  fitted  for  steering  right  and  left,  as  in 
the  case  of  the  rudder  of  a  ship  or  boat,  and  these  rudders 
are  connected  with  the  gyroscope.  If,  then,  it  is  desired 
to  fire  the  torpedo  on  a  certain  course  and  cause  it  to  keep 
that  course,  the  gyroscope  is  set  spinning  in  the  plane  of 


Fig.  4 


the  course,  and  if  the  torpedo  swerves  to  either  side,  the 
resistance  of  the  spinning  gyroscope  moves  the  rudders  and 
steers  it  back.  If  we  wish  to  run  the  torpedo  for  a  short 
distance  and  then  cause  it  to  turn,  as  in  Fig.  3,  the  gyro- 
scope is  turned  into  the  plane  of  the  final  course  that  we 
wish  to  make  the  torpedo  take  up,  and  connect  the  rudders 
in  such  a  way  (by  means  of  appropriate  mechanism)  that 
the  gyroscope  will  take  control  of  the  steering  after  a  certain 
length  of  run  and  swing  the  torpedo  into  the  plane  in  which 
it  (the  gyroscope)  is  already  spinning. 


TORPEDOES 


231 


The  details  of  the  Obry 
mechanism  are  secret  and, 
of  course,  complicated,  and 
the  device  is  not  yet  en- 
tirely perfected.  There  is 
no  doubt,,  however,  of  its 
entire  practicability,  and  it 
will  probably  be  in  use 
within  a  very  short  time. 

Sinlcing  Gear. —  If  a 
loaded  torpedo  misses  its 
mark  and  fails  to  explode, 
it  would  be  left  floating, 
a  menace  to  friends  and 
foes  alike.  Arrangements, 
therefore,  are  provided, 
such  that  if  it  does  not 
strike  after  running  a 
certain  distance,  a  valve 
opens  automatically  and 
causes  it  to  fill  with  water 
and  sink. 

Launching  Tubes. — Tor- 
pedoes are  fire^  from  long 
tubes,  or  guns,  which,  how- 
ever, differ  from  ordinary 
guns  in  that  the  impulse 
they  give  to  the  torpedo  is 
sufficient  only  to  launch  it 
clear  of  the  ship  and  into 
the  water,  when  its  own 
engines  take  charge  and 
drive  it  forw'ards.  On  tor- 
pedo boats  and  torpedo- 
boat  destroyers  oven\-ater 
tubes  are  used ;  these  tubes 
are  on  deck,  and  are  en- 
tirely exposed  to  the  pro- 
jectiles of  an  enemy's  ship. 


232 


TORPEDOES 


If  a  projectile  strikes  the  fuse,  it  may  explode  the  torpedo  and 
so  destroy  the  boat  carr>-ing  it.  This  is  a  risk  that  must 
be  taken  by  vessels  of  this  class,  but  it  is  one  that  cannot 
properly  be  taken  by  larger  ships,  and  on  such  ships  tor- 
pedoes, if  carried  at  all,  are  carried  below  the  protective  deck 
and  are  fired  from  underwater  tubes.  Fig.  5  represents  an 
overwater  launching  tube  containing  a  torpedo  ready  for 
firing,  and  in  Fig.  6  is  shown  the  torpedo  just  clear  of  the  tube. 


An  overwater  tube  can  be  trained  and  pointed  like  a  gun, 
so  far  as  lateral  aim  is  concerned,  but  underwater  tubes  are 
fixed  and  can  be  pointed  only  by  the  steering  of  the  ship. 
In  the  case  of  an  underwater  tube,  special  arrangements  are 
required  to  keep  water  from  entering  the  ship  and  also  to 
prevent  the  nose  of  the  torpedo  from  being  thrown  oflf  by  the 
motion  of  the  ship  through  the  water,  thus  spoiling  the  aim. 

The  Torpedo  Director. — The  aiming  of  a  torpedo  from  a 
n-joving  ship  to  strike  another  moving  ship  calls  for  quick 


TORPEDOES 


233 


and  accurate  estimate  of  the  speed,  course,  and  distance  of 
the  enemy,  and  accurate  knowledge  of  the  speed  of  the 
torpedo;  and  the  application  of  these  data  to  the  solutiori 


PosilionofEnemi/  X 
ea Instant  offiririf/  \\A 


•^ 


9 


l^ 


0^' 


DIRECTOR. 


DIRECTOR  ENLARGED. 


Position  ofEnemy\ 
allnsUuit  qfstriking\ 


Fig. 


of  a  triangle.  To  fire  directly  at  a  ship  i  mi.  distant  and 
moving  15  kn.  would  result  in  missing  the  mark  by  hun- 
dreds of  yards.  The  torpedo  must  be  aimed  ahead  of  him 
bv  an  amount  at  which  it  will  not  do  to  guess.     To  solve 


234  TORPEDOES 

the  problems  graphically,  the  torpedo  director.  Fig.  7,  has  been 
devised.  In  this  instrument,  three  bars  are  clamped  upon 
each  other  with  movable  clamps  that  may  be  secured  by 
setscrews.  One  bar  a  a'  is  graduated  for  the  speed  of  the 
enemy  and  is  laid  parallel  with  his  course.  The  second 
bar  h  b'  is  graduated  for  the  speed  of  the  torpedo.  The 
third  bar  c  c'  is  a  sighting  vane,  and  is  directed  toward  the 
enemy's  ship.  In  the  upper  diagram  of  Fig.  7  the  three 
lines  a  a',  b  b',  and  c  c'  represent  the  torpedo  director,  A  the 
position  of  the  enemy  at  instant  of  firing  the  torpedo,  and 
B  the  position  of  enemy  at  instant  of  striking.  The  only 
unknown  factor  in  connection  with  the  use  of  this  instrument 
is  the  speed  of  the  hostile  ship;  but  if  this  is  accurately 
estimated  (which  is  possible)  the  torpedo  stands  a  fair 
chance  of  striking  the  target. 

Torpedo  Boats. — There  has  been  much  discussion  within 
the  last  few  years  with  regard  to  the  advisability  of  fitting 
battleships  to  carry  torpedoes.  The  discussion  has  ended, 
so  far  as  the  United  States  Navy  is  concerned,  in  the  decision 
to  carry  them,  but  to  lise  underwater  tubes  only.  This 
decision  is  undoubtedly  wise,  but  it  is  none  ^the  less  true 
that  the  most  important  sphere  of  usefulness  for  the  torpedo 
is  found  when  it  is  used  by  a  torpedo  boat  against  a  battle 
ship  or  fleet  of  battle  ships.  A  ship  attacked  on  a  dark 
night  by  a  horde  of  these  little  crafts  closing  in  upon  her 
from  all  directions  without  warning  is  perhaps  in  the  most 
dangerous  position  in  which  she  could  be  placed.  The 
effective  range  of  the  torpedo  is  not  less  than  1,500  yd., 
and  at  that  distance  there  is  little  hope  of  seeing  a  torpedo 
boat  even  with  the  aid  of  a  searchlight.  If  the  boat  is  seen, 
the  defense  of  the  battle  ship  lies  in  the  rapid  fire  of  her 
light  guns,  but  the  chance  that  they  will  hit  so  small  and 
indistinct  an  object  at  a  range  of  nearly  a  mile  and  inflict  such 
damage  as  to  render  the  torpedo  boat  ineffective,  is  very 
slight;  and  where  a  large  number  of  boats  attack  at  once, 
their  success  should  be  almost  assured.  The  torpedo  of  the 
present  is  a  vastly  more  dangerous  weapon  than  that  of  even 
a  few  years  ago;  and  in  the  naval  warfare  of  the  future  its  his- 
tory will  be  very  different  from  what  it  has  been  in  the  past. 


SHIP  BUILDIXG  235 

SHIP  BUILDING 


PRINCIPLES  OF  CONSTRUCTION 

To  design  and  build  a  floating  structure  that  will  afford 
comfortable  living  accommodation  for  many  hundreds  of 
persons,  convenient  storage,  not  only  for  the  necessaries  of 
life  for  this  community,  but  for  great  quantities  of  freight, 
with  space  for  engines  and  boilers  powerful  enough  to 
drive  the  whole  mass  through  the  water  at  two-thirds  the 
speed  of  an  express  train,  as  well  as  space  for  the  fuel  needed 
to  maintain  this  speed  for  long  periods  of  time;  to  make 
this  structure  strong  enough  to  withstand  the  shocks  of 
the  heaviest  gales  and  to  have  a  hope  of  living  safely  through 
the  heavier  shock  of  grounding  or  collision;  all  this  is  a  task 
•whose  magnitude  can  hardly  be  overstated.  And  if  to  these 
requirements  we  add  the  manifold  items  demanded  by  the 
offensive  and  defensive  features  of  a  man  of  war,  we  have 
what  may  not  unreasonably  be  regarded  as  the  most  com- 
plex problem  of  creative  work  with  which  the  human  mind 
is  called  upon  to  deal. 

Preliminary  Considerations. — In  designing  a  ship,  it  is 
necessarj'  first  of  all  to  form  some  idea  of  the  size  and  weight 
that  she  will  have;  the  weight  to  include  not  only  the  ship 
proper,  but  the  full  load  that  she  is  to  carry.  It  is  a  prin- 
ciple of  hydrostatics  that  any  floating  body  will  settle  in 
the  water  until  the  part  of  it  which  is  immersed  displaces 
a  volume  of  water  exactly  equal  in  weight  to  the  whole 
of  the  floating  body.  If,  then,  a  ship  is  to  weigh,  complete, 
10,000  T.,  the  volume  of  that  part  which  is  to  be  below  the 
water  line  must  be  exactly  equal  to  the  volume  of  10,000  T. 
of  water.  Provided  that  this  volume  is  kept  constant, 
the  factors  of  it  may  be  varied  by  making  the  immersed 
body  long  and  fine  and  deep,  or  short  and  broad  and  shallow. 
In  and  upon  the  underbody  thus  fixed  the  weights  are  to 
be  distributed.  In  this  distribution,  if  the  ship  is  a  man  of 
war,  comes  an  inevitable  conflict  between  the  demands  for 
hea\T  guns,  for  thick  armor,  for  powerful  engines,  and  for 


236 


SHIP  BUILDING 


large  coal  supply,  which  must  be  settled  by  a  compromise 
dictated  by  considerations  of  the  special  duty  for  which  the 
ship  is  to  be  used. 

Stability. — In  the  arrangement  of  the  weights  and  the 
dimensions  of  the  hull,  the  first  consideration  is  the  stability 
of  the  ship;  or,  in  other  words,  its  safety  from  the  possi- 
bility of  capsizing.  The  stability  depends  on  what  is 
called  the  metacentric  height,  which  may  be  thus  explained. 
Suppose  that  the  ship  is  lying  at  rest  in  the  water  and  in  an 
upright  position,  as  in  Fig.  1  (a).     The  center  of  gravity  is 


Fig.  1 


at  G,  and  we  may  consider  the  whole  weight  of  the  ship  to 
be  concentrated  at  this  point  and  acting  downwards.  This 
downward  force  is  balanced  by  the  buoyancy  of  the  immersed 
section,  constituting  an  upward  force  that  may  be  considered 
as  concentrated  at  B,  the  center  of  figure  of  the  immersed 
section.  These  forces  being  equal  and  opposite,  and  acting 
along  the  same  straight  line,  the  body  remains  at  rest. 
If  the  ship  is  inclined — as  she  continually  will  be  by  the 
action  of  winds  and  waves  and  many  other  causes — the 
center  of  gravity  remains  where  it  was  before  (unless  there 
is  some  shifting  of  weights),  but  the  center  of  buoyancy 


SHIP  BUILDING  237 

changes  its  position  because  the  form  of  the  immersed 
section  has  been  changed,  Fig.  1  (6).  Suppose  that  the 
new  position  is  at  C;  now,  the  weight  of  the  ship  is  at  G, 
acting  downwards  as  before,  but  the  buoyancy  acts  upwards 
through  C,  on  one  side  or  the  other  of  G.  The  distance 
G  Z  between  the  Hnes  of  action  of  G  and  (7  is  a  lever,  at 
the  ends  of  which  these  forces  act  to  turn  the  ship.  In  this 
case,  the  line  C  Z  M,  along  which  the  buoyancy  acts,  cuts 
the  original  line  of  its  action  G  B  a.t  the  point  M.  This- 
point  is  called  the  metacenter.  Since  it  is  above  G,  the 
forces  that  act  on  the  ship  when  inclined  from  the  vertical 
will  tend  to  bring  her  back  to  an  upright  position,  and  the 
ship  will  be  stable;  that  is,  when  she  is  heeled  or  rolled  ta 
either  side  the  forces  called  into  action  will  bring  her  back 
to  an  upright  position.  If  the  line  CZM  should  cut  the; 
line  G  B  at  a.  point  below  G,  the  force  called  into  play  when- 
the  ship  was  heeled  or  rolled  would  act  to  heel  her  still 
farther,  and  she  would  capsize.  As  the  center  of  gravity 
of  a  given  ship  cannot  be  varied  greatly  in  the  design  of 
the  hull  (since  we  must  assume  an  approximate  distribution 
of  weights  as  decided  upon),  the  position  of  G  is  fixed,  and 
the  designer  must  shape  his  under-water  hull  so  as  to  place 
the  center  of  buoyancy  in  such  a  position  that  the  meta- 
center will  be  far  enough  above  the  center  of  gravity  to 
give  the  ship  a  strong  disposition  to  return  to  an  upright 
position  when  moved  out  of  this  position  by  any  change 
whatever.  The  height  of  the  metacenter  above  the  center 
of  gravity  is  called  the  metacentric  height. 

A  ship  that  has  a  considerable  metacentric  height  is  stiff, 
but  not  steady.  She  will  not  roll  ver>^  deeply,  but  she  will 
roU  very  quickly.  As  quick  rolling  is  unfavorable  for  gun 
fire,  men  of  war  are  usually  given  rather  slight  metacentric 
height,  and  this  has  in  some  cases  been  carried  so  far  as  to 
reduce  the  stability  beyond  the  point  of  safety.  It  is  sup- 
posed to  have  been  this  defect  of  design  that  caused  the 
capsizing  of  the  British  battle  ship  "Captain,"  in  the  Bay 
of  Biscay  on  Sept.  1,  1870.  This  ship  had  a  verj^  slight 
metacentric  height  and  rolled  little  and  slowly;  but  when 
she  found  herself  in  a  seaway  that  rolled  her  in  spite  of 


238 


SHIP  BUILDING 


her  sluggishness,   she  had   not   s-afficient   righting  moment 
(or  righting  leverage)  to  return  to  an  upright  position. 

Strain. — It  is  clear  that  a  structure  designed  to  meet  the 
strains  to  which  a  ship  is  subjected  must  have  great  strength. 
At  one  instant,  the  ship  may  be  resting  on  the  crest  of  a 
wave,  Fig.  2  (a),  which  supports  her  amidships,  while  the 
ends  hang  altogether  unsupported;  an  instant  later,  the  ends 


(b) 

Fig.  2 

may  be  buoyed  up  and  the  midship  section  unsupported, 
as  in  Fig.  2  (&).  And  the  strains  created  thus  are  only  a 
few  of  the  total  strains  that  will  be  felt  by  a  ship  rolling 
and  pitching  in  a  sea,  while  being  driven  through  it  by  her 
powerful  engines. 

Composition  of  the  Hull. — In  the  following  brief  descrip- 
tion of  the  most  important  features  of  a  ship,  reference  will 
be  made  to  Figs.  3  and  16,  representing  the  midship  section 
of  a  small  steamer  of  very  simple  construction.  Following 
the  description  of  this,  note  will  be  made  of  departures 
from  this  type  in  the  more  elaborate  construction  of  large 
merchant  vessels  and  men  of  war. 

The  frame  is  built  of  three  principal  parts:  two  angle 
bars,  with  their  flanges  facing  each  other,  connected  by  a 
vertical  floor  plate  of  iron  or  steel  riveted  along  its  edges 
to  the  flanges  of  the  angle  bars,  as  shown  in  section  at 
B  C,  Fig.  3.  The  outer  angle  bar  is  technically  the  jrame 
bar,   the  inner  one    the    reverse   bar.      The   space    between 


SHIP  BUILDIXG 


239 


the  bars  is  greatest  at  the  midship  line,  and  is  gradually 
reduced  toward  the  turn  of  the  bilge,  above  which  point 
the  bars  come  together  and  are  riveted  to  each  other, 
flange  to  flange,  the  floor  plate  being  dispensed  with, 
as  shown  in  section  taken  at  ^4  B.  The  frames  are  con- 
tinuous from  gunwale  to  gunwale,  crossing  the  keel  with- 
out a  break.       (This  is  not  true  of    ships    having    double- 

Guriiva/e  Bar  ^  ^ 

,i/^perDeckS/rif^'r 


,  fieverse  frame 

Sec/tonaf 
A-B 


P///ar- 


Dec/t  S^r/»^er  P/a/e 


Peverse  Pram. 


B/^eAee/so/? 


\ 


Rei'erse  Frame 


'  Cg/fferMee/scn- 


F/oorP/a/e^ 


"iS/e/e  /nfercos/a/  /^ee/s 


Fig.  3 

bottoms,  as  will  be  seen  hereafter.)  The  keel,  in  this  case 
a  har  keel.  Fig.  4,  extends  fore  and  aft  throughout  the 
length  of  the  ship,  being  made  up  of  as  long  sections  as 
can  be  obtained.  The  frames  are  rigidly  secured  to  it  by 
the    first   strake    of    the     outside    plating,   known    as    the 


240 


SHIP  BUILDING 


Cenfer  Kee/son 


garboard  strake.  This  strake  is  bent  like  an  angle  iron,  one 
flange  (narrow)  being  riveted  to  the  sides  of  the  keel,  while 
the  other  and  much  broader  flange  is  riveted  to  the  frame 
and  the  adjoining  strakes  of  plating  as  shown  in  detail  in 
Fig.  5  (a).  In  {h)  and  (c)  of  the  same  figure  is  shown  a  second 
and  third  type  of  keel,  known,  respectively,  as  the  side-bar  keel 
and  flat-plate  keel.  Above  the  floor  plates  lies  another  longi- 
tudinal girder,  running  the  whole  length  of  the  ship.  This 
is  the  main  or  center  keelson.  It  is  secured  to  the  frames, 
binding  them  rigidly  together,  and  forms,  with  the  keel, 
the  backbone  of  the  ship.  The  longitudinal  framing  further 
includes  a  number  of  side  keelsons  and  stringers,  some 
running  the  full  length  of  the  ship,  others  a  part  of  the 
length  only.  And  here  it  may  be  noted  that  all  longitudinal 
girders  on  the  bottom  of  the  vessel 
are  called  keelsons,  and  those  on 
the  sides,  above  the  hWga,  stringers. 
At  some  distance  on  each  side  of 
the  center  line  comes  the  side  keel- 
son, worked  intcrcostally;  that  is, 
in  short  lengths  between  the 
frames  —  intercostally  being  thus 
distinguished  from  continuous. 
The  sections  of  this  keelson  are 
very  firmly  secured  to  the  frames 
and  the  bottom  plating,  and  add 
greatly  to  the  longitudinal  strength 
of  the  ship,  though  less  than  if  they 
were  continuous.  The  method  of  securing  the  side  keelson 
to  the  frames  by  angle  bars  is  shown  in  Fig.  3.  Outside  the 
side  keelson  comes  the  bilge  keelson,  which,  being  on  top  of 
the  floor,  is  continuous;  and  along  the  side  above  the  bilge 
is  a  side  stringer.  (In  a  larger  ship  there  would  be  several 
of  these.)  The  legs  of  the  frames  are  tied  together  across 
the  ship  by  beams,  one  of  these  being  used  for  every  second  or 
third  frame.  The  beams  connect  with  the  frames  by  bracket 
plates,  or  knees,  riveted  to  both.  As  the  beams  not  only 
resist  the  tendency  of  the  frames  to  open  out  but  also  keep 
them  from  closing  in,  they  serve  as  both  ties  and  struts. 


Fig.  4 


SHIP  BUILD  I XG 


241 


The  decks  are  laid  over  the  beams  and  add  much  to  the 
longitudinal   stiffness.     They  are   reenforced   by   a   special 


F/afP/afeKeef. 
Fig.  5 
string  piece,  broad  and  flat,  laid  along  the  beams  through- 
out the  length  of  the   ship,  and  known  as  a  deck  stringer  . 
This  acts  like   the   deck  planking,  but  is  heavier,  and  is, 


242 


SHIP  BUILDING 


moreover,  founo  running  along  every  tier  of  beams,  even 
if  these  beams  do  not  carry  a  deck.  At  their  forward  ends, 
the  keel  and  center  keelson  are  connected  to  the  stem, 
which  is  in  fact  a  vertical  continuation  of  these  girders  at 
the  bow  of  the  ship.  At  the  after  end,  they  are  secured 
to  the  foot  of  the  rudder  post,  as  indicated  in  Fig.  6.  At 
both  bow  and  stern,  additional  strength  is  given  by  heavy 
triangular  pieces  called  "breasthooks,"  Fig.  8,  set  into  the 

angle  that  terminates  the 
body  of  the  ship,  and  con- 
necting the  ends  of  the 
stringers  already  described. 
Fig.  7  is  a  view  of  the  stern 
of  a  vessel,  taken  in  dry- 
dock,  showing  rudder,  star- 
board propeller,  and  the 
plating  riveted  \o  the  stern 
parts. 

The  construction  that 
has  just  been  described  is 
that  of  a  very  simple  mer- 
chant vessel.  In  larger 
vessels,  there  are  wide 
divergencies  from  this,  but 
the  general  principles  are 
not  greatly  different.  One 
of  the  most  important 
divergencies  is  the  double- 
bottom  construction,  used 
with  many  merchant 
steamers  for  carrying  water  or  ballast,  and  in  men  of  war 
to  give  security  in  case  of  grounding  and  of  damage  by  tor- 
pedoes.    Figs.  9  and  14  illustrate  this  construction. 

In  Fig.  9  we  note  that  the  keel  is  of  the  flat  type,  similar 
to  the  one  shown  in  Fig.  5  (c),  and  that  the  center  keelson, 
instead  of  standing  on  top  of  the  floors,  is  directly  above 
the  keiel  and  riveted  to  it;  also,  that  it  cuts  through  the 
frames,  being  itself  a  continuous  girder  throughout  the 
length  of  the  ship.     The  same  is  true  of  the  five  longitudinals 


Cue^ee/f- 


SHIP  BUILDING 


243 


that  w Jl  be  seen  between  the  center  keelson  and  the  armored 
deck.  It  follows  that  the  frames  in  this  part  of  the  ship 
cannot  be  continuous,  but  must  be  worked  intercostally 
between  the  longitudinals.  This  detracts  somewhat  from 
the  transverse  stiffness'  of  the  ship,  but  is  very  favorable 
to   longitudinal    strength.     Moreover,    extreme   precautions 


Fig.  7 
are  taken  to  make  the  joints  as  strong  and  rigid  as  possible. 
This  construction  is  confined  to  that  part  of  the  ship  (about 
two-thirds  of  the  total  length)  that  has  a  double-bottom 
proper.  Beyond  this  part,  at  both  bow  and  stem,  the 
frames  are  made  continuous,  and  the  longitudinals  (except 


244  SHIP  BUILDING 

the  center  keelson)  are  intercostal.  A  comparison  of  Fig.  14 
with  Fig.  15  will  show  other  points  of  difference  between  the 
framing  along  the  midship  portions  and  at  the  ends,  which 
cannot  be  described  here  for  lack  of  space.  In  Fig.  10  is 
shown  a  construction  in  which  a  water-tight  platform  run- 
ning throughout  the  length  of  the  ship  forms  a  double 
bottom. 

In  Fig.  9  the  double  bottom  extends  on  each  side  of  the  keel 
to  the  fourth  longitudinal,  which  thus  forms  the  side  bound- 
ary of  the  water-tight  cellular  construction.  These  longitudi- 
nals are  therefore  made  water-tight  by  very  careful  construc- 
tion and  by  calking.  The  center  keelson  and  the  second 
longitudinal  on  each  side  are  also  made  water-tight,  so  that 

the  double  bottom  is 
divided  longitudinally 
into  four  sections,  two 
on  each  side  of  the  keel. 
o^  •  Of  J  ^    ^<^(^y^»>.  The  third  longitudinal 

\       Wi%%^hm^  1^  g'&qvl  side  has  open- 

ings through  which  the 
9reas/^oo^  water  can  pass  and 
through  which  a  man 
can  crawl  for  purposes 
of  cleaning  and  inspec- 
tion. Similarly,  every 
Fig.  8  fourth  or  fifth  frame 

throughout  the  double-bottom  is  made  solid  and  water-tight, 
the  others  having  manholes  like  those  in  the  longitudinals. 
The  actual  construction  of  the  open  frames  is  shown  in  Fig.  1 1 . 
where  c  is  the  frame  bar,  h  the  reverse  bar,  and  a  a  bracket- 
plates  corresponding  to  the  floor  plates  of  Fig.  3. 

In  Fig.  12  is  shown  a  ship  in  process  of  construction,  giving 
an  excellent  view  of  the  framing  and  the  double-bottom  con- 
struction. In  this  ship,  the  third  longitudinal  on  each 
side,  very  conspicuously  shown,  forms  the  boundary  of  the 
double-bottom,  and  the  first  and  second  longitudinals  do 
not  run  throughout  the  whole  length  of  the  ship. 

The  outside  plating  is  riveted  to  the  frames,  and  adjoin- 
it?g  plates  are  riveted   to  each  other.     Several  methods  of 


SHIP  BUILDING 


245 


bringing  the  edges  of  the  plates  together  are  shown  in 
Fig.  13.  It  will  be  clear  that  the  plating  must  add  very 
much  to  the  strength  of  the  ship,  both  longitudinally  and 
transversely. 

Compartments. — A  ship  is  divided  internally  into  com- 
partments for  various  purposes  by  bulkheads  (partitions), 
some  running  longitudinally  and  others  transversely.  These, 
being  riveted  solidly  to  the  frames,  beams,  etc.,  add  very 
greatly   to   the    strength   and   stiffness  of  the  ship. 


y^e  /<ee/ 


In  all  modem  steamers,  a  certain  number  of  the  bulk- 
heads are  made  water-tight,  to  prevent  the  flooding  of  the 
whole  ship  from  a  leak  in  one  compartment.  In  men  of 
war,  the  water-tight  compartments  are  very  numerous. 
Communication  is  afforded  by  means  of  doors,  also  water- 
tight, which  in  the  most  recent  ships  can  be  closed  by  an 
electrically  governed  mechanism  operated  from  the  bridge. 


246 


SHIP  BUILDING 


Well  up  toward  the  bow  is  a  bulkhead  of  exceptional  strength, 
known  as  the  "collision  bulkhead,"  designed  to  afford  security 
in  the  event  of  a  head-on  collision. 

It    is    important    that    the    water-tight    compartments 


Fig. 10 

should  not  be  too  large,  and  this  is  especially  true  of  those 
which  are  near  the  ends  of  the  ship  or  which  are  confined 


Fig. 11 
to  one  side.     The  flooding  of  a  single  very  large  compart- 
ment  on    the    starboard    bow    of    the     British    battleship 
"Victoria"  led  to  the  capsizing  of  that  ship  when  she  was 


SHIP  BUILDING 


247 


k 


i 


^-W . ' 


#-B' 


Fig. 12 


248 


SHIP  BUILDING 


rammed  by  the  "Camperdown"  in  1893.  Had  the  "Victoria" 
had  no  water-tight  compartments  at  all,  she  would  doubtless 
have  sunk,  but  the  catastrophe  would  not  have  been  so 
sudden,  and  the  loss  of  life  much  less. 

The  interior  division  of  a  man  of  war  is  necessarily  more 
complicated  than  that  of  a  merchant  steamer.  This  sub- 
division, together  with   many   other  interesting   details   of 


/nner  S/ra/ees  Oout/e^ 
ro  Secure /7us/>  C>u/erSuf;fyee. 


the  structure  of  a  man  of  war,  is  shown  in  Figs.  14, 15,  and 
16,  which  are  reproduced  from  Knight's  "Modern  Seaman- 
ship" by  the  courtesy  of  the  D.  Van  Nostrand  Company,  pub- 
lishers. The  elaborate  bracing  shown  in  Fig.  15  is  needed  to 
strengthen  the  bow  for  ramming. 


SHIP  BUILDING 


249 


Lightening  Holes 

SVid  Beams 


Fig. 14 


250  SHIP  BUILDING 

Many  men  of  war  have  heavily  armored  decks  protecting 
their  vital  parts — that  is,  their  engines  and  boilers,  ammuni- 
tion rooms,  etc.  This  deck  is  nearly  flat  amidship,  but 
curves  down  toward  the  side  to  meet  the  upper  edge  of  the 
side  armor.  Such  a  deck  may  be  rather  thin  on  the  flat 
part,  but  must  be  thicker  on  the  slopes,  as  here  a  shell  stri- 
king it  would  have  a  more  direct  impact. 

The  side  armor  rests  upon  an  armor  shelf  built  into  the 
frames,  which  is  shown  in  Figs.  9  and  14.  The  armor  is 
secured  by  heavy  bolts  running  through  a.  thick  backing  of 
teak,  and  screwed  into  the  inner  face  of  the  armor  plate. 

Armor. — The  armor  of  modem  ships  is  invariably  of  steel, 
and  is  subjected  to  special  treatment  to  give  it  the  qualities 
that  are  found  to  be  necessary  for  resisting  the  impact  of 
heavy  shells.  These  qualities  are,  first,  hardness,  to  resist 
penetration,  and  second,  toughness,  to  resist  breaking  up. 
These  qualities  are  antagonistic  to  each  other;  ordinarily, 
a  steel  that  is  tough  is  rather  soft,  while  one  that  is  hard  is 
almost  necessarily  brittle.  The  armor  primarily  used  for 
ships  was  of  wrought  iron,  which  was  toiigh  but  soft. 

The  first  steel  armor — introduced  a  quarter  century  ago — 
was  much  like  wrought  iron,  though  inferior  to  it.  There  was 
no  difficulty  about  making  hard  steel,  but  this  was  too  brittle. 
The  first  move  toward  combining  the  two  properties  consisted 
in  welding  a  hard  steel  face  on  a  tough  wrought-iron  back. 
This  compound  armor,  as  it  was  called,  gave  good  results,  the 
hard  face  resisting  penetration,  and  the  soft  back  holding  the 
plate  together.  In  more  recent  years  a  better  solution  of 
the  problem  has  been  found  in  making  a  homogeneous  plate 
of  steel,  and  hardening  the  face  of  it  by  a  special  process 
of  tempering.  Two  such  processes  have  been  invented,  the 
Harvey  and  the  Krupp.  These  processes  give  a  plate  in  which 
the  hard  face  and  the  tough  back  are  combined  without  the 
weld,  which  was  a  plane  of  weakness  in  the  old  compound 
plate.  In  comparing  armor  plates  with  each  other,  it  is  con- 
venient to  refer  their  resisting  power  to  that  of  wrought  iron, 
since  this  is  almost  perfectly  uniform,  and  its  characteristics 
do  not  change  from  year  to  year.  Accordingly,  we  say  that 
Harveyized  armor  has  a  resisting  power  of  2  (or  a  figure  of 


SHIP  BUILDIXG 


Wood  Deck  Plank. 
Deck  Plahng 


Deck  Plating 


Fig. 15 


252 


SHIP  BUILDING 


Hammoch  Cloth 
y — -Spar  Deck  ^ 


f -Covering  Plate- 
/  Hammock 
Berthing 

HammocH  . 
Berthinq 

••^"FJ^Sft^n^a 
■  'aterWau 
-Beam 
Arm 


Fig.  16 


SHIP  BUILDING  253 

merit  of  2),  meaning  that  a  given  thickness  has  a  power  of 
resistance  equal  to  twice  that  thickness  of  wrought  iron. 

The  very  latest  and  best  armor  made,  which  is  treated 
by  the  Krupp  process,  or  Kruppized,  has  a  resisting  power 
of  2.5,  and  the  turrets  of  our  latest  battle  ships,  the  "Con- 
necticut" and  "  Louisiana,"  which  carry  10  inches  of  this 
armor,  have  the  same  resisting  power  as  if  they  were  cov- 
ered with  wrought  iron  25  inches  thick. 


NOTES  RELATING  TO  SPEED,  TON- 
NAGE, AND  COAL  CONSUMPTION 
OF  A  STEAM  VESSEL 


SPEED  OF  VESSELS 

The  exact  amount  of  power  required  to  propel  a  vessel 
at  a  given  speed  cannot  be  deduced  very  readily  from  the 
elementary'  principles  of  mechanics.  Instead,  we  must  relv 
on  empirical  rules  based  on  the  actual  performance  of  vessels. 
The  conditions  that  influence  the  relation  between  power 
and  speed  are  many,  but  only  a  few  of  the  more  important 
ones  will  be  enumerated  here.  For  instance,  the  area  of  the 
blades  of  the  screw  propeller  may  not  be  sufficient  for  high 
speed,  owing  to  a  churning  of  the  water  when  the  propeller  is 
revolved  beyond  a  certain  number  of  revolutions.  Although 
the  power  expended  in  revolving  the  propeller  faster  may  be 
considerable,  the  increase  of  the  speed  may  be  very  slight. 
A  similar  state  of  affairs  may  occur  if  the  area  of  the  buckets 
of  a  paddle  wheel  is  too  small.  It  may  be  large  enough 
for  a  low  rate  of  speed,  and  still  be  entirely  too  small  for 
a  higher  rate,  thus  showing,  probably,  a  high  efficiency  of 
the  propelling  instrument  at  a  low  speed,  and  a  very  poor 
one  at  a  higher  rate.  Again,  the  efficiency  of  the  engine 
may  vary  greatly  for  different  powers  developed  by  the 
same  engine. 

For  these  reasons  no  positive  rule  can  be  framed  that 
will  express  the  relations  between  power  and  speed  under 


254  SPEED,  TOXXAGE, 

all  conditions.  By  the  following  rule,  however,  the  approx- 
imate number  of  horsepower  (I.  H.  P.)  required  to  propel  a 
vessel  at  a  certain  speed  may  be  found: 

Rule. — Multiply  the  cube  of  the  speed  by  the  cube  root  of 
the  square  of  the  ship's  displacement,  in  tons;  divide  the  product 
by  the  constant  corresponding  to  the  length,  speed,  and  shape 
of  the  vessel. 

Let  /.  H.  P.  =  indicated  horsepower; 

Z)  =  displacement  of  vessel,  in  tons; 
X  =  constant  referred  to; 
5  =  speed,  in  knots  per  hour. 
The  above  rule  expressed  algebraically  is  then  as  follows: 

The  terms  used  in  this  formula  are  explained  in  the  order 
in  which  they  appear. 

Indicated  Horsepower. — An  engine  generally  absorbs  a 
certain  amount  of  the  work  done  by  the  steam  owing  to 
friction  of  pistons,  rods,  and  wearing  surfaces.  The  actual 
useful  or  net  work  put  ftut  by  the  engine  is  for  this  reason 
less  than  that  done  by  the  steam  on  the  pistons.  The  pres- 
sure acting  on  the  pistons  is  ascertained  by  attaching  to 
the  cylinder  an  instrument  called  the  indicator,  which 
registers  on  a  sheet  of  paper  the  variation  of  the  steam 
pressure.  The  amount  of  power  calculated  from  the  mean 
effective  pressure  obtained  from  the  indicator  card  by 
means  of  the  indicator  is  known  as  the  indicated  horse- 
power of  the  engine. 

Displacement.  —  In  the  technical  sense  in  which  this 
teriTi  is  applied  to  ships  or  any  other  floating  bodies,  dis- 
placement  refers  to  the  displacement  of  the  water  by  the 
total  or  partial  immersion  of  any  object  placed  in  it.  The 
volume  of  water  displaced  may  be  measured  in  cubic  feet 
or  in  tons,  and  the  weight  of  water  displaced  (which  is  equal 
to  the  weight  of  the  floating  object)  is  called  the  displace- 
ment. 

Constant. — The  constant  employed  in  the  formula  is 
found  in  the  following  table: 


AND  FUEL  CONSUMPTION 

TABLE    OF    CONSTANTS 


255 


Description  of  Vessel 

Speed 
Knots 

i- 

Under  200  ft.,  fair   .     . 

9-10 

9-10 
10-11 
11-12 

9-11 

9-11 
11-12 

9-11 
11-13 

9-11 
11-13 
13-15 

9-11 
11-13 
11-13 
13-15 
15-17 
15-17 

i  200 

Under  200  ft.,  line 

2SU 

Under  200  ft.,  fine 

210 

Under  200  ft.,  fine \    .    .. 

200 

From  200-250  ft     fair.    .    . 

220 

From  200-250  ft.,  fine 

240 

From  200-250  ft     fine. 

1   220 

From  250-300  ft.,  fair 

1   250 

From  250-300  ft.,  fair 

220 

From  250-300  ft.    fine 

260 

From  250-300  ft.,  fine 

240 

From  250-300  ft.,  fine 

200 

From  300-400  ft.,  fair 

260 

From  300-400  ft     fair 

240 

From  300-400  ft.,  fine 

260 

From  300-400  ft     fine   .... 

240 

From  300-400  ft.,  fine 

190 

Above  400  ft    fine 

240 

To  determine  whether  a  vessel  is  fair  or  fine,  it  is  usual 
to  compare  its  displacement,  in  cubic  feet,  with  the  volume 
of  a  rectangular  box  having  a  length  equal  to  the  length 
of  the  vessel  on  the  water-line,  a  width  equal  to  the  beam, 
and  a  depth  equal  to  the  draft  of  the  vessel  diminished  by 
the  depth  of  the  keel.  If  the  displacement  is  .55  of  the 
volume  of  the  box,  or  less,  the  vessel  is  fine;  if  above  .55  and 
less  than  .70,  it  is  fair.  The  quotient  obtained  by  dividing 
the  displacement  by  the  contents  of  the  imaginary  box  is 
called  the  coefficient  of  fineness. 

Illustration. — To  illustrate  the  application  of  the  given  rule, 
suppose  that  a  vessel  260  ft.  long  and  finely  shaped  is  to  have 
a  speed  of  15  kn.;  what  should  be  the  indicated  horsepower 
of  the  engine,  assuming  the  vessel  to  have  a  displacement  of 
1,000  T?  From  the  table,  we  find  X  =  200.  Inverting  values 
in  the  given  formula,  we  find  the  required  horsepower  to  be 
153xf'l,000"2  ^ 3,375X100 
200  200 


/.  H.  P. 


1,687.5.     Ans. 


256  SPEED,   TONNAGE, 

TONNAGE  AND  DISPLACEMENT 

By  the  application  of  a  simple  method  known  as  Simpson's 
rules,  the  volume  of  the  immersed  portion  of  a  ship  can  be 
ascertained;  which,  if  considered  as  water  and  divided  by  35, 
will  give  the  displacement,  in  tons.  But  as  vessels  vary 
considerably  in  form,  the  mere  length,  beam,  and  draft  of 
a  ship  cannot  be  utilized  for  finding  the  displacement; 
hence,  the  coefficient  of  fineness  previously  mentioned  must 
be  used  in  the  computation  of  displacement.  Knowing  the 
extreme  dimensions  of  a  vessel  and  its  coefficient  of  fineness, 
the  exact  displacement  is  readily  found.  For  example, 
take  a  vessel  100  ft.  long,  20  ft.  beam,  and  floating  at  8  ft. 
draft,  the  coefficient  of  fineness  being  .6,  the  displacement 

^.jj^^  100X20 X8X_-6  =  274.3  T. 
oo 

Tonnage  refers  to  the  internal  capacity,  or  volume,  of  a 
ship.  A  glance  at  a  tonnage  certificate  or  a  register  of 
shipping  for  any  vessel  shows  two  distinct  classes  of  tonnage, 
viz.,  gross  and  net  tonnage. 

Gross  tonnage  is  the  entire  internal  capacity  measured 
according  to  certain  rules,  as  specified  in  the  navigation  laws 
of  the  United  States,  and  according  to  size  and  type  of  vessel. 

Net  tonnage  is  the  remainder  after  having  taken  from  the 
gross  tonnage  allowances  for  crew  space,  engine  and  boiler- 
room,  shaft  alley,  etc.  The  net  tonnage  is  supposed  to 
represent  the  earning  capacity  of  the  ship,  and  it  is  there- 
fore made  the  basis  for  port  and  navigation  charges.  The 
detailed  rules  for  computing  tonnage  are  quite  complicated, 
and  do  not  come  within  the  scope  of  this  pocketbook. 
They  will  be  found,  however,  in  the  navigation  laws  of  the 
United  States,  or  under  the  Revised  Statutes,  Chap.  I, 
Title  XLVIII,  Sec.  4.150  to  4.153,  and  Chap.  398.  If  it  be 
required  to  ascertain  the  tonnage  of  a  vessel,  the  best  thing 
to  do  is  to  submit  the  drawings  and  plans  to  the  nearest 
local  inspector  of  the  United  States  Steamboat  Inspec- 
tion Service. 

Displacement,  which  is  often  confused  with  tonnage,  is, 
as  stated  before,  the  weight  of  the  water  that  the  ship  dis- 
p!:..js,  or,  what  is  the  same  thing,  the  weight  of  the  ship 


AXD  FUEL  CONSUMPTIOX  257 

itself  and  everything  on  board.  Hence,  the  displacement  of 
a  vessel  varies  from  day  to  day.  or  from  one  voyage  to 
another,  according  to  the  cargo,  coal,  stores,  etc.  on  board, 
while  tonnage,  being  determined  by  the  type  and  internal 
dimensions  of  the  ship,  remains  constant.  When  the 
dimensions  and  capacity  of  a  certain  ship  are  required,  it  is 
usual  to  give  the  displacement  as  well  as  the  gross  and  net 
tonnage  of  the  ship.  Thus,  the  internal  capacity  of  the 
steamship  "Dakota,"  belonging  to  the  Great  Northern  Steam- 
ship Company,  is  given  as  follows:  Gross  tonnage,  21,000; 
net  tonnage,  13,500;  displacement,  37,500  gross  tons.  The 
port  and  navigation  charges  for  this  vessel  are  therefore 
based  on  13,500  net  tonnage. 

PROBLEMS  ON  SPEED 

Very  often  the  question  as  to  the  number  of  revolutions  at 
which  the  engine  must  be  run  to  drive  the  vessel  at  a  certain 
speed  comes  up  before  those  in  charge  of  a  steamer.  If  the 
revolutions  per  minute  of  the  engine  for  a  certain  speed  of 
the  vessel  are  known,  the  question  may  be  readily  answered. 
Assuming  the  percentage  of  slip  to  remain  constant,  doub- 
ling the  velocity  of  the  stream  projected  by  the  propelling 
instrument,  that  is,  doubling  the  revolutions  of  the  engine, 
and  hence  of  the  screw  propeller  or  paddle  wheels,  doubles 
the  speed  of  the  vessel.  In  other  words,  the  speed  varies 
directly  as  the  revolutions  of  the  engine. 

By  the  term  slip  is  understood  the  velocity  of  the  stream 
projected  by  any  propelling  instrument,  in  reference  to  the 
surrounding  water,  in  a  direction  opposite  to  that  in  which 
the  ship  moves.     Since  the  actual  velocity  of  the  stream 
cannot  be  obtained  by  calculation,  it  has  become  a  common 
practice  to  consider  the  pitch  of  the  propeller  P  multiplied 
by  the  revolutions  per  minute  R  as  the  speed  of  the  stream. 
Under  this  assumption,  slip  may  be  defined  as  the  difference 
between  the  theoretical  speed,  P'  expressed  by  the  formula 
_    PXJ?X60 
6,080 
and  the  actual  speed  of  the  vessel,  in  knots  per  hour;  or,  the 
difference  between  the  speed  of  a  vessel  corresponding  to 


258  SPEED.  TOXXAGE, 

the  product  of  pitch  of  the  propeller  and  the  number  of 
revolutions  in  a  given  time,  and  the  actual  speed  of  the 
vessel  in  the  same  time. 

The  slip  is  usually  expressed  in  per  cent,  of  the  velocity 
of  the  stream  propelling  the  vessel. 

In  actual  practice  the  percentage  of  slip  varies  some- 
what at  different  speeds  and  under  different  conditions; 
hence,  the  following  rule,  which  is  based  on  the  assumption 
of  a  constant  percentage  of  slip,  does  not  give  the  ciact 
number  of  revolutions  per  minute  required.  This  can  be 
found  only  by  actual  trial.  However,  it  will  give  a  very 
fair  approximation. 

Rule. — To  find  the  number  of  revolutions  per  minute  at  which 
to  run  the  engine  in  order  to  give  the  required  speed,  divide  the 
product  of  the  revolutions  producing  any  given  speed  and  the 
required  speed  by  the  given  speed. 

Let  i^  =  revolutions  per  m.inute  for  a  given  speed; 
5  =  given  speed; 
R\  =  required  revolutions; 
5i  =  required  speed; 
then,  the  given  rule,  expressed  algebraically,  will  be 

Ri  =  -^ 

Example. — If  a  vessel  is  propelled  at  a  rate  of  16  kn. 
when  the  engine  is  making  32  rev.  per  min.,  what  should 
be  the  number  of  revolutions  per  minute  to  reduce  the 
speed  to  14  kn.? 

Solution. — Applying  the  above  rule,  we  find 

„      32X14     __  .  . 

Ri  = — Tp —  =28  rev.  per  mm.     Ans. 

Number  of  Revolutions  Propeller  Should  Make  to  Run  at 
Required  Speed,  the  Pitch  of  Propeller  Being  Known. — In 
order  to  solve  this  problem,  the  slip  of  the  propeller  for 
the  required  speed  must  be  known ;  and  if  not  known  from 
trial-trip  records,  must  be  assumed  at  a  conservative  figure. 
The  slip  of  well-designed  propellers  varies  between  5  and 
15%,  the  average  being  about  10%.  Owing  to  the  slip  of 
the  propeller,  it  must  be  run  at  a  higher  number  of  revolu- 
tions than  would  be  the  case  otherwise. 


AND  FUEL  COXSUMPTION  259 

Let  P  =  pitch  of  propeller,  in  ft.; 
X  =  required  speed,  in  knots; 
7?  =  re  volutions  per  minute  at  required  speed; 
A^  =  number  of  feet,  in  a  knot  (6,080); 
5  =  per  cent,  of  slip,  expressed  as  a  decimal. 
The  number  of  revolutions  for  the  required  speed  is  then 
found  by  the  proportion  QOX  P:N  =  K:RX(.1—S);  whence, 
„  6,080 XiC  ,  .,     60XPXi?X(l-S) 

^  =  60XPX(l-5)'^"^^ 6:080 

Example  1. — The  pitch  of  a  propeller  is  16  ft.;  how  many 
revolutions  per  minute  must  it  make  to  drive  the  ship  at 
the  rate  of  10  kn.  per  hour,  the  slip  being  estimated  at  10%? 
Solution. — Applying    the    first    formula    given,    and    sub- 
stituting values,  we  get 

„  6,080X10  __.  .  1  A 

^^60X16X(l-.l)  =  '°'  ''''■  P^^  "^^"-  "^"^^^'-     '^"'- 
Example  2. — A  propeller  having  a  pitch  of  20  ft.  makes 
70  rev.  per  min.;  from  a  trial-trip  record,  the  slip  is  known 
to  be  12%  at  that  number  of  revolutions.     What  is  the  speed 
of  the  ship  ? 

Solution. — Applying  the  second  formula  given,  we  get 
^     60X20X70X<1-.12)      ,^.^,  ,  . 

K  = QQSO ^  ^^^  ' 


FUEL  CONSUMPTION  AND  SPEED 

The  fuel  consumption  may  be  said  to  vary  directly  as  the 
horsepower  developed  (this  is  not  exactly  true,  but  only 
approximately).  The  horsepower  varies  directly  as  the  cube 
of  the  speed,  whence  it  follows  that  the  fuel  consumption 
will  also  vary  as  the  cube  of  the  speed  (approximately). 
Let  S  =  certain  speed  of  vessel; 

C"  =  coal  consumption  at  speed  S; 
5  =  new  speed; 
c  =  coal  consumption  at  speed  5. 

Then,  c  =  -^ ,  and  -^  =  A  7=^ 


•260  FUEL  CONSUMPTION  AND  SPEED 

Example  1. — A  steamer  consumes  100  T.  of  coal  per  da. 
at  a  speed  of  10  kn.;  what  should  be  the  speed  in  order  to 
cut  the  coal  consumption  down  to  50  T.  per  da.? 

Solution. — Using  the  second  formula,  we  find 


5  =  -v/ —  =  f^ 500  =  7.9,  or  8  kn.,  nearly.     Ans. 

Example  ?. — A  steamer  consumes  80  T.  of  coal  per  da.  at  a 
speed  of  12  kn.  per  hr. ;  suppose  that  the  speed  is  to  be  reduced 
to  10  kn.  per  hr. ;  what  would  be  the  fuel  consumption  per 
da.  at  that  rate  of  speed? 

Solution. — Using  the  first  formula,  we  find 

103X80      1,250  ■     .  oT  ^    ■      A 

<:  =  ^^-  =  -2^=44.8T.  per  da.     Ans. 

Example  3. — If  a  steamer  consumes  15  T.  of  coal  per  da.  to 
produce  a  speed  of  9  kn.  per  hr.,  how  many  knots  would  she 
steam  if  the  coal  consumption  were  reduced  to  12  T.  per  da.  ? 

Solution. — In  this  case,  c  =  12,  5  =  9,  and  C=15.  Inserting 
these  values  in  the  second  formula,  we  find  the  new  speed,  or 

3/12x93      3/4X729      a,v^-i,     001       . 
5  =  -%/ — i-^ —  =-%/ =-—  =  F  583.2  =  8.3  knots  per  hr., nearly. 

Ans. 

Example  4- — A  steamer  consumes  20  T.  of  coal  per  da.  at 
a  normal  speed  of  10  kn.  per  hr.  The  distance  to  the  nearest 
port  where  coal  can  be  had  is  600  mi.,  and  the  estimated 
quantity  of  coal  in  the  bunkers  is  but  35  T.  Find  what 
•speed  should  be  maintained  in  order  to  reach  the  coaling 
station  with  the  coal  supply  on  hand. 

Solution. — The  best  way  to  proceed  in  a  case  of  this  kind 

is  to  assume  a  lower  speed,  say  8  kn.,  and  calculate  the  new 

.-       .u  .  A     .u  83X20     256 

■coal    consumption    tor    that    speed;    thus,    c=      „ — ~"o^ 

=  10.24  T.  per  da.,  or  .43  T  per  hr.  The  time  required  to 
cover  a  distance  of  600  mi.  at  a  speed  of  8  kn.  per  hr.  is 
'8*'  =  75  hr.,  and  at  a  coal  consumption  of  .43  T  per  hr.  the 
total   quantity   of   coal   required   at   that   speed   is   75  X  .43 

=  32}  T.  Hence,  if  a  speed  of  8  kn.  per  hr.  is  maintained, 
the  supply  of  coal  on  hand  (35  tons)  will  suffice  to  reach  the 
coaling  station  under  ordinary  weather  conditions.     Ans. 


ROPES  261 

In  practice  it  is  advisable  to  have  a  good  margin  of  coal 
in  excess  of  the  calculated  amount,  for  the  reason  that  the 
actual  coal  consumption  at  the  reduced  speed  will,  as  a  rule, 
exceed  the  calculated  consumption  because  of  the  decrease  in 
economy  of  the  engine,  induced  by  reducing  the  developed 
horsepower. 


ROPES 

Ropes  in  general  use  on  shipboard,  in  reference  to  the 
material  from  which  they  are  made,  are  of  three  kinds: 
hemp,  manila,  and  wire  ropes.  Although  wire  rope  is  rapidly 
superseding  all  other  kinds,  even  for  certain  running  gears, 
fiber  ropes  are  still  used  very  extensively,  and  for  certain 
purposes  can  never  be  replaced  by  steel  ones. 

Fiber  Ropes. — The  very  best  of  the  fibers  used  in  the 
manufacture  of  cordage  is  the  so-called  manila  fiber,  which 
is  obtained  from  the  leaf  stalks  of  the  Musa  textilis,  or  textile 
banana,  the  entire  supply  of  which  comes  from  the  Philip- 
pine Islands.  This  fiber  is  very  strong  and  durable,  but  not 
ver>'  flexible,  and,  therefore,  is  not  well  adapted  to  the  man- 
ufacture of  small  cordage,  though  it  is  ver>'  satisfactory  for 
the  larger  sizes.  When  dry  it  contains  12%  moisture,  and 
will  absorb  as  much  as  40%  in  a  damp  atmosphere;  moist- 
ure, however,  does  not  tend  to  promote  the  decay  of  this 
fiber.  In  fact,  in  hot,  dry  weather  an  occasional  wetting  of 
the  rope  is  thought  to  prolong  its  life.  A  freezing  tempera- 
ture renders  the  fiber  brittle.  The  hardest  and  strongest 
fiber  is  that  from  the  outer  layer  of  leaf  stalks;  that  from 
the  inner  layers  is  increasingly  fine  and  weak.  The  butts 
of  the  fibers  are  stronger  than  the  tops. 

Next  in  importance  is  the  common  hemp,  which  is  the  fiber 
of  the  stalk  of  the  plant  of  that  name.  It  is  grown  through- 
out Europe,  in  India,  and  in  some  parts  of  America.  The 
kind  best  adapted  to  the  manufacture  of  cordage  is  that 
grown  in  Russia.  This  fiber  is  more  flexible  than  manila 
fiber,  but  less  strong  and  less  durable.  It  decays  very 
rapidly  if  kept  wet.  A  tarred  hemp  rope  immersed  in  water 
is  stated  to  have  lost,  in  4  mo.,  nine-tenths  of  its  strength. 


262 


ROPES 


Hemp  rope  used  on  shipboard  is  invariably  tarred.  The 
tar  acts  as  a  preservative  on  the  rope,  but  has  a  tendency  to 
slightly  reduce  its  strength  and  flexibility;  the  use  of  tar 
in  standing  rigging  also  serves  to  diminish  contraction  and 
expansion  due  to  wet  and  dry  weather.  It  is  advisable  that 
a  tarred  hemp  rope  should  not  be  used  until  6  mo.,  or  even 
1  yr.,  after  its  manufacture.  This  period  of  rest  allows  the 
tar  to  become  uniformly  distributed  throughout  the  fiber, 
and  the  English  Admiralty  Board  states  that  the  rope  has 
10%  greater  durability  than  if  it  is  used  as  soon  as  made. 
Manila  ropes  are  never  tarred.  Hemp  rope  when  not  tarred 
is  known  as  white  rope. 

Coir,  the  fiber  of  the  outer  husk  of  the  cocoanut,  is  occa- 
sionally used  in  cordage  manufacture,  it  is  quite  strong,  but 
is  short,  stiff,  coarse,  and  rough.  On  account  of  its  buoy- 
ancy, and  because  moisture  does  not  affect  it,  rope  made  of 
coir  is  particularly  well  adapted  for  tow  ropes. 

In  manufacturing  rope,  the  fibers  are  first  spun  into  a 
yam  twisted  right  hand.  From  20  to  80  of  these  yarns  are 
twisted  together  left  hand  to  form  a  strand.  Three  or  four 
strands  are  then  twisted  right  hand  into  a  rope.  Ropes 
composed  of  four  strands  generally  have  a  center,  or  core, 

consisting  of  a  small 
rope  about  which  the 
strands  are  laid.  (See 
b.  Fig.  1.)  This  cen- 
ter rope  is  called  the 
Jteart.  The  primary 
object  of  the  twisting 
is  to  hold  the  fibers 
in  place,  so  that  each 
may  do  its  share  of 
the  work.  When  the 
strands  are  twisted  up  left  hand,  the  yams  are  untwisted, 
but  when  the  rope  is  twisted  up  right  hand  the  strands 
are  untwisted  and  the  yarns  again  twisted  up.  There  is 
thus  a  certain  degree  of  equilibrium  that  the  rope  maker 
endeavors  to  attain,  at  which  the  tendencies  of  the  rope 
and    the    strands    to    untwist    are    equal    in    amount    and 


Fio.  1 


ROPES  263 

opposite  in  direction.  If  the  twist  is  great,  the  rope  is 
hard  and  stiff,  and  keeps  its  form  well,  but  it  is  not  so  strong 
as  a  rope  with  less  twist. 

Hawser  and  Cable. — A  rope  of  3  strands  is  called  a  hawser, 
a.  Fig.  1.  A  rope  of  4  strands  is  said  to  be  shroud  laid,  b, 
Fig.  1.  Very  large  ropes  are  made  by  twisting  3  hawsers 
together  to  form  a  cable,  as  in  c.  Fig.  1. 

As  a  rope  bends  over  sheaves  and  drums,  the  fibers  slide 
on  one  another,  and  are  thus  worn  out  quite  rapidly,  espe- 
cially near  the  heart  of  the  rope;  a  rope  will  therefore  last 
much  longer  if  it  runs  over  large  sheaves.  Rope  is  desig- 
nated by  its  circumference,  expressed  in  inches,  and  is 
issued  in  coils  of  about  113  fathoms  each. 

Small  Stuff  is  the  name  given  to  various  small  ropes  used 
on  shipboard;  they  are  distinguished  by  the  number  of 
strands  and  yams  used  in  their  make  up.  Thus,  ratline, 
used  principally  for  seizings  and  rattling  down  the  rigging, 
is  composed  of  3  strands  twisted  right  hand,  each  strand 
containing  from  4  to  8  yams.  Spun  yarn  is  spun  left  hand, 
and  consists  usually  of  three  yarns;  it  is  used  extensively 
for  various  purposes,  such  as,  seizings,  mousings,  to  serve 
ropes,  etc.  Rope  yarns  are  mostly  made  from  condemned 
tarred  hemp  rope;  this  too  is  a,  very  much  needed  article 
around  deck  and  aloft.  A  man  should  never  go  aloft 
without  a  supply  of  rope  yams;  he  will  find  them  very  useful 
in  fixing  up  and  strengthening  worn-out  mousings,  stops,  etc. 

Wire  Rope. — Wire  from  which  ropes  are  manufactured  is 
commonly  either  of  iron  or  of  steel.  Steel  wire  has  nearly 
displaced  iron,  as  it  has,  for  most  purposes,  many  advantages. 
Iron  wire  ropes  are,  however,  stUl  made  and  used.  The 
only  iron  suitable  for  this  use  is  the  best  quality  of  charcoal 
iron,  and  most  manufacturers  advertise  that  they  use 
Swedish  charcoal  iron,  the  malleable  iron  made  from  the 
pure  ores  of  Sweden  having  acquired  an  excellent  reputation 
throughout  the  world. 

The  greatest  strength  in  a  wire  rope  would  be  attained 
by  laying  the  component  wires  parallel,  and  the  strength 
of  the  cable  would  then  be  equal  to  the  sum  of  the  strengths 
of   the    individual   wires   composing   it.     Suspension-bridge 


264 


ROPES 


cables  are  actually  constructed  in  this  way,  but  this  system 
of  construction  is  not  suitable  for  running  ropes.  Such  a 
cable  is  a  mere  bundle  of  wires;  it  has  no  stability  of  form 
and  would  spread  out  laterally  where  it  came  in  contact 
with  a  sheave  or  drum.  The  wires  would  rub  against  one 
another,  wear  rapidly,  and  probably  be  broken  one  at  a 
time  by  kinking  or  by  catching  on  something.  In  order  to 
overcome  these  objections,  wire  ropes,  other  than  those 
for  large  suspension  bridges,  are  made  up  somewhat  after 
the  model  of  the  hemp  rope;  i.  e.,  by  twisting  together  a 
certain  number  of  wires  to  form  a  strand,  and  a  certain 
number  of  strands  to  form  the  rope.  In  recent  years,  a  num- 
ber of  special  rope  sections  have  been  introduced.  The 
wires  composing  a  rope  are  all  circular  and  of  the  same 
diameter,  the  prevailing  geometrical  form  of  the  rope  section 


Fig.  2 


being  the  hexagon.  The  simplest  form  of  rope  strand  is 
composed  of  7  wires,  arranged  as  in  Fig.  2  (a);  6  of  these 
strands  are  commonly  arranged  around  a  core  of  tarred 
hemp  to  form  the  rope.  This  rope  is  largely  used  for  trans- 
mission purposes  in  manufacturing  establishments,  and  for 
shrouds,  stays,  etc.  of  the  standing  rigging  of  a  ship. 
Fig.  2  (&)  shows  a  rope  consisting  of  6  strands,  each  being 
made  up  of  12  wires,  laid  around  a  hemp  center;  this  con- 
struction makes  an  extremely  flexible  and  very  light  rope, 
and  is  used  almost  exclusively  for  running  gear  on  ship- 
board. In  (c)  is  shown  the  type  of  construction  known  as 
the  special  flexible  hoisting  rope  consisting  of  6  strands  of 
37  wires  each,  laid  about  a  hemp  center,  combining  extreme 
flexibility  and  high  tensile  strength.  It  is  used  largely  on 
cranes,   derricks,   and   dredges,   and  when   galvanized  it  is 


ROPES  265- 

frequently  employed  with  great  success  for  towing  hawsers. 
Fig.  2  {d)  shows  the  ordinary  hoisting-rope  construction. 
The  6  strands  consist  of  19  wires  each,  laid  around  a  hemp 
center.  This  construction  combines  flexibility,  needed  for 
the  rope  to  pass  over  drums  and  sheaves,  and  high  tensile 
strength.  It  is  probably  the  most  universally  applicable  of 
any  form  of  rope. 

In  special  types  of  wire  ropes,  the  hemp  heart  is 
replaced  by  a  core  of  wire.  Such  ropes  are  much  stiffer 
than  those  with  hemp  cores,  and  are  only  adapted  for  use 
as  standing  ropes.  The  substitution  of  the  wire  for  the 
hemp  core  adds  about  10%  to  the  weight  of  the  rope,  but 
does  not  add  materially  to  its  strength.  This  is  because 
the  wires  in  the  central  strand,  making  a  smaller  angle 
with  the  axis  of  the  rope  than  those  in  the  outside  strands, 
are  not  able  to  accommodate  themselves  to  the  stretching  of 
the  rope  under  load  and,  therefore,  carry  an  undue  pro- 
portion of  the  load,  breaking  before  the  wires  are  fully 
loaded. 

Protection  of  "Wire  Rope. —  Ropes  used  on  shipboard  are 
mostly  made  of  galvanized  wire,  the  purpose  being  to  pre- 
vent corrosion  by  protecting  the  iron  or  steel  of  the  wire 
against  contact  with  air  or  water.  Galvanizing  accomplishes 
this  in  the  case  of  standing  ropes,  but  is  not  effective  for 
running  ropes.  The  friction  of  the  rope  against  sheaves, 
drums,  or  anything  else  with  which  it  comes  in  contact, 
soon  wears  off  a  portion  of  the  zinc,  and  with  both  zinc 
and  iron  exposed  and  in  contact  with  water,  corrosion 
proceeds  more  rapidly  than  it  would  if  the  zinc  were  not 
present.  A  further  objection  to  the  galvanizing  process  is 
that  the  necessary  heating  of  the  wire  has  the  effect  of  par- 
tially annealing  it  and,  consequently,  reducing  its  strength. 

Various  preparations  are  used  for  coating  wire  rope  to 
prevent  corrosion  due  to  exposure  to  water  and  dampness. 
The  most  easily  applied,  and  as  effective  as  any,  while  it 
sticks,  is  raw  linseed  oil.  The  chief  objection  to  its  use 
is  that,  being  a  liquid,  it  runs  or  is  washed  off  the  rope  in  a 
short  time,  necessitating  another  treatment,  in  default  of 
which  the  wires  are  soon  corroded.     In  order  to  partially 


266 


ROPES 


meet  this  objection,  the  oil  is  sometimes  mixed  with  its 
weight  of  lampblack,  thus  giving  it  more  body.  The  liquid 
condition  of  the  pure  oil  is,  however,  a  great  advantage,  as 
the  oil  finds  its  way  readily  into  the  interior  of  the  rope, 
and  the  inside  wires  are  thus  effectively  protected. 

MANILA  ROPE 


Circum- 

Weight 

Breaking 

Strain 

ference  in 

per  Foot 

Inches 

in  Pounds 

Tons 

Pounds 

1 

.019 

.28 

560 

1 

.033 

.39 

784 

li 

.074 

.78 

1,568 

2 

.132 

1.36 

2,733 

2i 

.206 

2.14 

4,278 

3 

.297 

3.06 

6,115 

3i 

.404 

4.27 

8,534 

4 

.528 

5.78 

11,558 

4i 

.668 

7.39 

14,784 

5 

.825 

9.18 

18,368 

5i 

.998 

10.97 

21,952 

6 

1.190 

12.77 

25,536 

6^ 

1.390 

14.50 

29,120 

7 

1.620 

16.35 

32,704 

7h 

1.860 

18.14 

36,288 

8 

2.110 

19.93 

39,872 

9 

2.670 

23.52 

47,040 

10 

3.300 

27.10 

54,208 

11 

3.990 

30.69 

61,376 

12 

4.750 

34.27 

68,544 

13 

5.580 

37.86 

75,712 

14 

6.470 

41.44 

82,880 

NoTB. — For  safe-working  load,  allow  from  one-fifth  to  one-seventh  of  the 
breaking  strain. 

Pine  tar,  applied  hot,  is  sometimes  used,  and  one  appli- 
cation will  last  a  long  time  on  account  of  the  viscous,  sticky 
nature  of  the  material.  For  the  same  reason,  however,  the 
preservative  does  not  so  readily  reach  the  interior  of  the 
rope.  Coal  tar  aLso  is  used  for  this  purpose.  In  order  to 
neutralize  any  acid  that  may  be  contained  in  either  pine 


ROPES 


267 


or  coal  tar,  it  is  usual  to  add  slacked  lime,  in  the  proportion 
of  about  1  bu.  to  1  bar.  of  tar.  The  mixture  is  boiled  thor- 
oughly before  application.  Sawdust  is  sometimes  added,  to 
give  additional  body. 


GALVANIZED  IRON  WIRE  ROPE 

(Used  for  Shrouds  and  Stays) 

Composed  of  6  Straxds  axd  Hemp  Cexter,  With  7  or  12 

Wires  to  the  Strand 


Circumference 

Circum- 
ference in 
Inches 

Weight 
per  Foot 
in  Pounds 

Breaking 

Strain 

Tons  of 

2,000  lb. 

of  New 

Manila  Rope 

of  Equal 

Strength 

Inches 

.16 

1.4 

2 

u 

.20 

1.8 

It 

.25 

2.3 

.36 

3.2 

3 

If 

.49 

4.4 

31 

2 

.64 

5.8 

4i 
4f 

2i 

.81 

7.3 

2i 

1.00 

9.0 

5 

2f 

1.21 

11.0 

5i 

3 

1.44 

13.0 

51 

3i 

1.70 

15.0 

6 

3i 

1.95 

18.0 

n 

3f 

2.25 

20.0 

4 

2.55 

23.0 

8 

4i 

2.90 

26.0 

8i 

4i 

3.25 

29.0 

9 

4f 

3.60 

32.0 

9* 

5 

4.00 

36.0 

10 

5i 

4.40 

40.0 

lOi 

5i 

4.85 

44.0 

11 

XoTE. — For  safe-working  load,  allow  from  one-fifth  to  one-seventh  of  the 
breaking  strain. 

The  preceding  and  following  tabular  statements  relating 
to  the  weight  and  breaking  strain  for  different  sizes  of  wire 
ropes  have  been  furnished  by  the  makers,  principally  by 
Messrs.  John  A.  Roebling  Sons,  Trenton,  N.  J.,  and  should 
for  this  reason  be  considered  comparatively  trustworthy. 


268         .  ROPES 

GALVANIZED  STEEL  HAWSERS 

(Used  extensively  for  towing) 

Composed    of     6   Strands    and   a    Hemp    Center.    Each 

Strand  Consisting  of  12  Wires  and  a  Hemp  Core 


Circumference 

Circum- 

Weight 

Breaking 
Strain 

of  New  Manila 
Hawser  of 

ference  in 

per  Foot 

Equal 
Strength 

Inches 

in  Pounds 

Tons  of 
2,000  lb. 

Inches 

2i 

.54 

12.3 

5* 

2i 

.67 

14.4 

6 

21 

.81 

16.4 

6i 

3 

.97 

21.5 

8 

3i 

1.14 

24.0 

8i 

3 

1.32 

27.0 

81 

3 

1.51 

29.0 

9i 

4 

1.72 

32.0 

10 

4i 

1.94 

39.0 

11 

4i 

2.18 

42.0 

IH 

4| 

2.42 

45.0 

12 

5 

2.70 

53.0 

12i 

5i 

2.95 

57.0 

13 

5i 

3.25 

61.0 

13i 

STEEL  HAWSERS  FOR  HEAVY  TOWING 

Composed  of  6  Strands  and  a  He.mp  Center,  37  Wires 
to  the  Strand 


Circum- 

Weight 
per  Foot 

Breaking  Strain,  in  Tons 

ference  in 

Inches 

in  Pounds 

Cast-Steel 

Special 

3 

1.44 

31 

40 

3i 

1.95 

42 

55 

4 

2.55 

55 

72 

n 

2.90 

62 

81 

3.60 

76 

99 

5 

4.00 

84 

109 

tt 

4.85 

101 

131 

6.25 

128 

166 

Note, — For  safe-working  load,  allow  from   onc-flftli  to  one-seventh  of  the 
breaking  strain. 


GALVANIZED  CAST-STEEL  WIRE  ROPE        269 

(Used  for  Yacht  Rigging) 
Composed  of  6  Straxds  and  Hemp  Center,  7  or  19  Wires 

TO    THE    StRAXD 


Circumference 

Circum- 

Weight 

Breaking 
Strain 

of  New 
Manila  Rope 

ference  in 
Inches 

per  Foot 
in  Pounds 

Tons  of 
2,000  lb. 

of  Equal 

Strength 

Inches 

.16 

3.7 

3 

Is 

.20 

4.5 

3i 

.25 

5.7 

4^ 

}! 

.30 

6.8 

4. 

.36 

8.1 

4J 
5k 

.49 

10.8 

2 

.64 

14.0 

6 

2i 

.81 

17.6 

7 

2i 

1.00 

22.0 

8 

2| 

1.21 

26.0 

8i 

3 

1.44 

31.0 

9 

3i 

1.70 

36.0 

10 

3^ 

1.95 

41.0 

11 

3f 

2.25 

47.0 

12 

4 

2.55 

53.0 

13 

GALVANIZED  IRON  AND  CAST-STEEL  WIRE  ROPE 

(Used  for  Running  Gear) 
Composed  of  6  Strands  and  Hemp  Center,  Each  Strand 


Consisting  of  12  W 

res  and  a 

Hemp 

Core 

Circum- 

Weight 
per  Foot 
in  Pounds 

Breaking  Strain 

ference  in 
Inches 

Iron 

Cast-Steel 

.11 

1.14 

2.28 

1| 

.13 

1.60 

3.20 

1* 

.17 

2.15 

4:30 

IX 

.24 

2.78 

5.56 

If 

.33 

3.47 

6.94 

2 

.43 

4.29 

8.58 

2{ 

.54 

6.13 

12.30 

2i 

.67 

7.20 

14.40 

2f 

.81 

8.21 

16.40 

3 

.97 

10.70 

21.50 

3i 

1.14 

12.00 

24.00 

NoT«. — For  safe-working  load,  allow  from   one-fifth  to  one-seventh  of  the 
breaking  strain. 


270  ROPES 

SPLICES  AND  BENDS 

Splicing  is  the  operation  of  joining  two  pieces  of  rope  so 
as  to  obtain  one  continuous  piece  with  no  appreciable 
increase  of  diameter  at  the  splice.  There  are  several  kinds 
of  splices  but  the  principal  ones  are  the  short  splice,  the 
long  splice,  and  the  eye  splice.  The  principle  of  all  splicing 
consists  of  joining  or  "marrying"  the  strands,  thinning 
them  out,  and  tapering  them  so  that  the  diameter  at  the 


Fig.  1 


splice  is  the  same  or  only  slightly  greater  than  that  of  the 
rope  itself.  In  the  long  splice,  no  increase  in  diameter  is 
allowed.  The  only  tools  necessary  for  splicing  hemp  or 
manila  ropes  used  for  ordinary  running  gears  are  a  marline- 
spike  and  a  knife.  The  marlinespike  is  made  of  either  iron 
or  hardwood,  is  from  12  to  14  in.  long,  and  about  1  in.  in 
diameter  at  the  thick  end,  the  other  end  being  sharpened  to 
a  blunt  point  about  as  shown  in  Fig.  1 ;  it  is  always  operated 
by  the  right  hand,  while  the  left  encircles  the  rope.  After 
pushing  the  extreme  point  through  between  the  strands  to 
be  separated,  the  thick  end  is  placed  against  the  body  of 


ROPES 


271 


the  operator;  then,  using  both  hands,  the  rope  is  twisted 
so  as  to  render  the  work  of  opening  the  strands  easy. 

The  marh'nespike  should  be  provided  with  a  good  laniard, 
attached  to  the  hole  in  its  thick  end,  and  when  vised  aloft  it 
should  be  slung  around  the  operator's  neck  or -secured  to  the 
rigging. 

The  Short  Splice. — To  make  the  short  splice,  unlay  the 
strands  at  the  end  of  each  rope  for  a  distance  about  as  shown 
in  Fig.  2;  this  distance  depends  entirely  on  the  diameter 
of  the  rope,  but  as  the  proportion  will  be  the  same  for  all 
diameters,  the  illus- 
tration serves  as  a 
general  guide ;  be 
sure  to  unlay  enough ; 
a  few  inches  too 
much  is  better  than 
too  little  as  the  ends 
have  t  o  b  e  cut  ofif 
anj^vay.  Then,  place 
the  two  ends  together 
as  shown  at  Fig.  2  (a) , 
so  that  each  strand 
lies  between  two 
strands  of  the  other 
rope.  Hold  the 
strands  x  y  z  and  the 
rope  .4   in   your  left 


^ssssssssssss 


(c) 
Fig.  2 


hand;   if  the  ^  o  p  e  s  ^^^g^^^^^^SSSSSSSSa 
are  too  large  to  hold  fc»=>*^^**"^ 

thus,  fasten  them  to- 
gether with  twine; 
then  take  one  of  the  strands,  say  «,  pass  it  over  strand  y, 
and,  having  made  an  opening,  either  wnth  the  thumb  or  with 
a  marlinespike,  in  the  manner  illustrated  in  Fig.  1,  push  this 
strand  n  through  under  x  and  pull  it  taut;  this  operation  is 
known  as  tucking.  Proceed  similarly  with  strands  m  and  o, 
passing  each  over  the  immediately  adjoining  strand  and 
under  the  next  one.  Perform  precisely  the  same  operation 
with  the  strands  of  the  other  rope,  passing  each  strand  over 


272 


ROPES 


the  adjoining  one  and  under  the  next,  thus  making  the  splice 
appear  as  at  Fig.  2  (b).  In  order  to  insure  security  and 
strength,  this  tucking  must  be  repeated  by  passing  each 
strand  over  the  third  and  through  under  the  fourth;  then, 
after  subjecting  the  spHce  to  a  good  stout  pull,  cut  off  the 
ends  of  the  strands,  and  you  have  the  finished  splice  as  shown 
at  Fig.  2  (c). 

In  slings  and  straps  used  for  heavy  work,  the  strands 
should  be  tucked  twice  each  way,  and  over  one-half  of  each 
strand  should  be  whipped,  or  bound,  with  twine  to  one-half 


Fig.  3 

of  the  rest,  in  order  to  prevent  the  strands  from  "creeping 
through"  when  the  splice  is  taxed  to  the  full  capacity  of 
its  strength. 

In  the  short  splice,  the  diameter  at  the  joint  is  greater 
than  that  of  the  rope,  for  which  reason  it  is  not  a  suitable 
splice  where  the  rope  is  to  be  used  in  tackles  and  pulley 
blocks,  or  in  places  that  will  not  admit  anything  larger 
than  the  rope  itself.  In  such  cases  the  long  splice  is  used; 
this,  when  properly  made,  the  untrained  eye  can  hardly 
distinguish  from  the  rest  of  the  rope. 

The  Long  Splice. — To  make  the  long  splice,  unlay  the 
ends  as  before,   but  about  three   times  as  far,   and  place 


ROPES 


273 


them  together,  as  shown  at  Fig.  3  (a),  in  the  same  manner 
as  for  the  short  spUce.  Then  unlay  one  of  the  strands, 
say  X  of  the  right-hand  rope,  and  in  the  groove  thus  made 
lay  the  strands  n  of  the  left-hand  rope,  taking  good  care  to 
give  this  strand  the  proper  twist,  so  that  it  falls  gracefully 
into  the  groove  previously  occupied  by  strand  x.  Do  like- 
wise with  strands  y  and  m,  unlaying  y  gradually  and  in  ifts 
place  laying  the  strand  m\  the  result  is  shown  at  Fig.  3  (&). 
Now,  leaving  the  middle  strands  p  and  g  in  their  original 
positions,  cut  off  all  the  strands  as  shown  at  (6) ;  then 
relieve  strands  n  and  x  of  about  one-third  of  their  yarns, 


and  with  what  is  left  cast  an  overhand  knot  as  shown — 
taking  care  that  the  knot  is  made  so  that  the  strands  will 
follow  the  lay  of  the  rope,  and  not  cross  it.  Pull  this  knot 
taut  and  dispose  of  the  ends  as  in  the  short  splice,  by  passing 
them  over  the  adjoining  strand  and  through  under  the 
next,  cutting  off  a  few  yams  at  each  tuck.  Proceed  similarly 
with  strands  p  and  g,  and  y  and  m.  The  splice,  when  it  is 
completed,  appears  as  at  Fig.  3  (c).  Sometimes  the  over- 
hand knot  is  made  without  first  thinning  the  strands,  and 
then  split,  and  the  half  strand  put  through  as  described; 
but  by  doing  so,  the  surface  of  the  splice  is  never  as  smooth  as 


274 


ROPES 


by  the  other  method,  which,  for  strength  and  neatness,  is 
second  to  none. 

The  Eye  Splice. — To  make  an  eye  splice,  unlay  the  strands 
about  as  far  as  for  the  short  splice,  and  bend  into  the  required 
size  of  eye,  as  shown  at  Fig.  4  (a).  Then  tuck  the  end  of 
the  middle  strand  y  under  one  of  the  strands  of  the  stand- 
ing part — having  previously  made  the  necessary  opening 
with  the  marlinespike — and  pull  taut,  getting  what  is  shown 
at  (6).  Push  the  strand  x  from  behind,  and  under  the  strand 
on  the  standing  part  next  above  that  under  which  the 
middle  strand  y  was  passed,  so  that  it  will  come  out  where 
>' went  in,  getting  what  is  shown  at  (c);  then  pass  the  third 
strand  z  under  the  remaining  free  strand  in  the  standing 
part,  next  to  the  one  under  which  y  was  passed,  getting  (d). 
Pull  the  strands  taut,  and  from  each  cut  out  one-third  of 
the  yams;  pass  each  remaining  two-thirds  over  the  adjoining 
strand  of  the  rope,  and  then  through  under  the  next,  as  in 
the  short  splice;  then  cut  off  one  half  of  the  yarns,  and  tuck 
the  other  half  under  its  correspond- 
ing strand  for  the  third  time ;  give  it 
a  good  stretching,  cut  off  the  ends, 
and  thus  complete  the  splice  as 
shown  at  {e)  Fig.  4. 

In  four-stranded  ropes,  the  short 
and  long  splice  are  made  essentially 
the  same;  in  the  eye  splice,  the  first 
strand  is  tticked  imder  two  strands 
of  the  rope,  the  second  tucking 
being  done  exactly  as  in  the  three- 
stranded  rope. 

The  Chain  Splice. — To  make  a 
cliain  splice,  unlay  the  strands  of  the 
rope  and  reeve  two  of  them  through 
the  end  link;  then  unlay  the  third  strand  for  about  the  dis- 
tance shown,  and  in  its  place  lay  one  of  the  other  strands,  the 
same  as  in  making  the  long  splice;  make  an  overhand  knot 
and  dispose  of  the  ends  in  the  usual  way;  dispose  of  the  third 
strand  x — one  of  the  two  reeved  through  the  link — as  when 
making  the  eye  splice,  by  "tucking"  near  the  link;  cut  off  the 


Fig.  5 


ROPES 


275 


ends,  and  the  splice  is  com- 
plete as  shown  at  Fig.  5  ib) . 
This  is  a  very  neat  and 
strong  splice,  and  can  be 
used  with  advantage  in 
connection  with  chains 
that  are  tailed,  or  length- 
ened, with  a  rope  that  has 
to  pass  through  sheaves  or 
places  that  do  not  allow 
any  increase  of  diameter  in 
the  rope. 

Splicing  in  Wire. — In 
making  a  long  splice  in 
wire  rope,  the  same  prin- 
ciples are  followed  as  in 
splicing  fiber  ropes.  The 
strands  are  unlaid,  inter- 
ne laced,  and  each  placed 
0  snugly  in  the  groove  made 
^  by  unlaying  the  opposing 
strand  whence  the  ends  are 
tucked  away  in  such  man- 
ner as  to  follow  the  lay  of 
the  rope.  Before  unlaying 
the  strands,  it  is  advisable 
always  to  put  on  a  good 
seizing  at  the  extremities 
of  the  intended  splice  in 
order  to  prevent  the  rope 
from  untwisting  farther 
than  is  desired.  The 
length  of  the  splice  de- 
pends, of  course,  on  the  size 
of  the  rope.  When  unlay- 
ing the  strands,  be  sure  to 
do  so  without  taking  the 
turn  out.  The  strands  may 
also  be  unlaid  in  pairs  and 


276 


ROPES 


singled  up  when  married.  The  hemp  heart  is  cut  out  close  to 
where  seizings  are  applied.  Before  tucking  away  the  ends, 
each  pair  should  be  approximately  at  equal  distances  from 
one  another,  as  shown  in  Fig.  6  (a).  The  beginning  of  an 
eye  splice  in  wire  is  shown  in  Fig.  6  (b).  When  the  size  of 
the  eye  is  fixed,  put  on  a  seizing  as  shown;  then  open  up  the 
standing  part  somewhat,  at  place  where  tucking  is  to  be 
done,  by  giving  the  rope  a  certain  amount  of  twist.  This 
will  render  the  tucking  comparatively  easy.  When  tuck- 
ing, have  3  strands  on  top  and  3  strands  underneath  the 


Fig.  7 


standing  part  (assuming  that  the  splicing  is  done  hori- 
zontally), and  dispose  of  them  in  such  manner  that  each 
strand  will  come  out  in  consecutive  order,  or  as  shown  in 
Fig.  6  (c).  It  does  not  matter  under  how  many  strands 
(one  or  two)  on  the  main  rope  they  pass  as  long  as  they 
come  out  in  their  proper  lay.  The  strands  are  now  tucked 
once  or  twice,  taking  care  not  to  make  the  tucks  too  short, 
in  which  case  the  splice  will  be  a  lumpy  one.  Then  hammer 
the  splice  with  a  wooden  mallet  and  trim  off  the  ends  snugly. 
The  short  splice  is  made  in  the  same  way  as  the  eye  splice. 


ROPES  277 

Splicing  in  wire  calls  for  special  tools,  such  as  are  shown  in 
Fig.  7,  and  a  certain  amount  of  skill,  which  can  be  acquired 
only  by  long  practice,  and  proper  training  by  a  capable 
instructor. 

BENDS  AND  HITCHES 

In  Figs.  1,  2,  and  3  are  shown  a  number  of  bends  and 
hitches  in  common  use  on  shipboard.  The  manner  in 
which  these  bends  are  made  is  evident  on  inspection  of  the 
illustrations,  and  hence  only  a  few  explanatory-  remarks 
concerning  the  use  to  which  some  of  them  are  put  will  be 
needed. 

The  reef  knot  is  the  best,  simplest,  and  most  used  method 
of  connecting  the  ends  of  two  ropes,  small-sized  cordage; 
the  granny  knot  is  undesirable  and  unprofessional  in  every 
respect;  it  slips  easily  and  is  hard  to  untie.  For  the  purpose 
of  attaching  two  ropes  of  different  size,  the  single  or  double 
sheet  bend  should  be  used.  The  double  carrick  bend  is 
sometimes  used  for  bending  two  hawsers  together.  The 
bowline  is  perhaps  the  most  useful  bend  ever  invented; 
it  can  be  applied  in  various  ways,  from  hoisting  a  man 
aloft  to  the  bending  together  of  two  hawsers.  To  make  it, 
take  the  end  of  the  rope  in  the  right  hand  and  the  standing 
part  in  the  left  and  lay  the  end  over  the  standing  part; 
then  with  the  standing  part  make  a  turn  or  loop  around  the 
end  and  pass  the  latter  over  and  around  the  standing  part 
and  back  through  the  bight  again,  thus  completing  the 
knot.  The  figure-of-eight  knot  turned  in  a  rope  will  prevent 
it  from  unreeving.  In  Fig.  2  are  shown  a  few  methods  of 
applying  a  rope  to  a  hook.  The  cross-hitch  is  used  for  a 
sling  or  strap  when  the  rope  spreads  away  to  its  load;  this 
hitch  prevents  the  sling  from  slipping  in  the  hook  in  case 
the  load  comes  in  contact  with  some  obstruction  while  being 
hoisted.  The  Blackwall  hitch  should  be  made  with  the  end 
twice  around  the  hook  as  shown,  except  for  very  light  loads; 
experience  has  proved  this  to  be  the  safest  way,  since  with 
only  one  turn  the  end  is  liable  to  "creep"  when  subjected 
to  a  heavy  strain,  especially  in  damp  weather  when  the 
moisture  absorbed  by  the  rope  serves  as  a  lubricant.  The 
sheepshank   is   useful   for   shortening  up   a   rope.     In   this 


278 


ROPES 


Sfuareor 
Reeff(not 


GnmnyKhof 


Snj/e  Sheet  Bemf 


Ooi/UeS/jeefffent/ 


Running  Bow//ne 


ROPES 


279 


Correct  anct  IVron^ 

to  belay  a  sheef 
o  ckat 


5/nf/e  Spanish        Runner  ana 

Burton.  7acAI&  OouMe  Spamsft 

Burton. 


Fig.  3 


ROPES 


Oi^erhand  Knot  tia// Jiitch  Halliard  Bend     Fishermans  Bend 


Timber  Hitch  Timber  and  Hal/  Hitch  C/oire  Hitch 


fiolling  Hitch         Ttvo  Hal/ Hitches       Hound  Turn  &  2  Hal/ Hitches 


Method  o/  Doubting 
C/inch  Round  Turn  &  Hal/ Hitch      Up  a  t^oorinff 

Fig.  3 


WIND  AXD  WEATHER  281 

figure  is  shown  also  the  correct  and  incorrect  way  of  fasten- 
ing a  rope — say  the  sheet  of  a  sail — to  a  cleat;  it  is  evident 
that  if  the  sheet  is  belayed  as  shown  on  lower  cleat,  the 
increased  strain  on  the  sail  will  jam  the  rope  and  render 
it  difficult,  if  not  impossible,  to  ease  off  the  sheet.  The 
bends  and  hitches  shown  in  Fig.  3,  do  not,  we  believe,  require 
any  explanation,  and  can  be  made  by  referring  to  the  illus- 
trations. 


WIND  AND  WEATHER 

Weather  Indications  by  a  Mercurial  Barometer. — The  use 

of  the  barometer  as  a  weather  glass  is  common  both  on  sea 
and  on  land.  But  only  those  that  have  long  watched  and 
carefully  compared  its  indications  with  the  prevailing 
weather  conditions  are  able  to  foretell  more  than  that  a 
rising  barometer  indicates  less  wind  or  rain;  a  falling 
barometer,  more  wind  or  rain,  or  both;  a  high  barometer, 
fine  weather;  and  a  low  one,  the  reverse.  But  useful  as  are 
these  general  conclusions  in  most  cases,  they  are  sometimes 
erroneous. 

By  attending  to  the  following  brief  observations,  any  one 
not  accustomed  to  the  use  of  a  barometer  may  do  so  with 
less  hesitation  and  with  immediate  advantage. 

The  column  of  mercury  in  a  good  barometer  usually 
stands,  on  an  average,  some  tenths  of  an  inch  higher  with 
or  before  polar  and  easterly  winds  than  it  does  with  or 
before  equatorial  and  westerly  winds  <of  equal  strength  and 
dryness  or  moisture)  in  all  parts  of  the  oceans.  The  terms 
polar  and  equatorial  are  here  used  with  reference  to  winds 
blowing  from  the  nearest  polar  direction,  or  from  the  equa- 
torial parts  of  the  earth. 

This  peculiarity  of  the  barometer  causes  many  mistakes 
to  be  made.  The  barometer  is  high,  perhaps,  but  falling. 
Wind  or  rain,  or  both,  are  expected  in  consequence,  yet 
neither  follows  to  any  decided  extent.  A  change  of  wind 
from  one  quarter  to  another  only  takes  place.  Reversely, 
the  barometer  is  low,  but  rising.  Fine  weather  is  expected; 
yet,  instead  of  that,  a  strong  wind,  accompanied  perhaps  by 


282  WIND  AND  WEATHER 

rain,  hail,  or  snow,  rises  from  the  polar  direction.  By  such 
changes  as  these,  seamen  are  often  misled,  and  calamity, 
caused  by  unpreparedness,  may  sometimes  occur  as  a 
consequence. 

There  may  be  heavy  rains  or  violent  winds  beyond  the 
horizon,  and  even  within  the  view  of  an  observer,  by 
which  his  instruments  may  be  affected  considerably,  though 
no  particular  change  of  weather  occurs  in  his  immediate 
locality.  Sometimes,  severe  weather  from  an  equatorial 
(southerly  in  north  latitudes,  northerly  in  the  southern 
hemisphere)  direction,  not  lasting  long,  may  cause  no  great 
fall  of  the  barometer,  because  followed  by  a  period  of  wind 
from  polar  regions;  and  at  times  the  mercurial  column  may 
fall  considerably  with  polar  winds  and  fine  weather,  appa- 
rently against  the  rule,  because  a  continuance  of  equatorial 
winds  is  about  to  follow. 

As  a  general  rule,  the  barometer  rises  for  northerly  winds 
(included  between  the  northwest  and  northeast),  for  dry 
or  less  wet  weather,  for  less  wind,  or  for  more  than  one  of 
these  changes,  except  on  a  few  occasions,  when  rain,  hail, 
or  snow,  with  a  strong  wind,  comes  from  the  north. 

The  barometer  falls  for  southerly  winds  (included  between 
the  southeast  and  southwest),  for  wet  weather,  for  stronger 
wind,  or  for  more  than  one  of  these  changes,  except  on  a 
few  occasions,  when  moderate  wind,  with  rain  or  show, 
comes  from  the  northward. 

There  is  little  variation  of  the  barometer  between  the 
tropics,  because  the  wind  blows  generally  in  the  same  direc- 
tion and  with  equal  force,  and  no  contending  currents  of  air 
cause  any  considerable  change  in  the  temperature  or  density 
of  the  atmosphere.  For  violent  storms  or  hurricanes,  how- 
ever, within  the  tropics,  the  barometer  falls  very  low,  but 
soon  returns  to  its  usual  state  after  the  storm  center  has 
passed. 

It  has  been  observed  on  some  coasts  that  the  barometer 
is  differently  affected  by  the  wind,  according  as  it  blows 
from  the  sea  or  from  the  land,  the  mercury  rising  on  the 
approach  of  the  sea  breeze  and  falling  previously  to  the 
setting  in  of  the  land  breeze. 


WIND  AND  WEATHER  283 

Indications  by  Appearance  of  Sky. — Some  young  seamen 
hardlj-  appreciate  sufficiently  common  rules  about  weather, 
which  are  as  true  as  they  are  trite;  namely,  that  a  red  sky 
at  sunset  presages  fine  weather;  a  red  sky  in  the  morning 
bad  weather  or  much  wind,  if  not  rain;  a  gray  sky  in  the 
morning,  fine  weather;  that  soft-looking  or  delicate  clouds 
foretell  fine  weather,  with  moderate  or  light  breezes;  hard- 
edged,  oily-looking  clouds,  wind;  that  a  dark,  gloomy  blue 
sky  is  windy,  but  a  light,  bright  blue  sky  indicates  fine 
weather;  that,  generally,  the  softer  the  clouds  look  the  less 
wind,  although  rain  may  be  expected;  and  the  harder,  more 
"greasy,"  rolled,  tufted,  or  ragged,  the  stronger  the  wind 
will  prove.  Also,  that  a  bright  yellow  sky  at  sunset  pre- 
sages wind;  a  pale  yellow,  wet;  and  that,  by  the  preponder- 
ance of  red,  yellow,  or  gray  tints  the  coming  weather  may  be 
foretold  very  nearly — indeed,  if  aided  by  instruments, 
almost  accurately. 

These  indications  of  weather,  afforded  by  the  colors  of 
the  sky,  seem  to  deserve  more  critical  study  than  has  yet 
been  given  to  the  subject. 

Indications  by  the  Aneroid  Barometer. — A  rapid  rise 
indicates  unsettled  weather. 

A  gradual  rise  indicates  settled  weather. 

A  rise,  with  dry  air  and  cold  increasing,  in  summer,  indi- 
cates wind  from  the  northward  in  north  latitudes,  but  from 
the  southward  in  south  latitudes;  and  if  rain  has  fallen, 
better  weather  may  be  expected. 

A  rise,  with  moist  air  and  a  low  temperature,  indicates 
wind  and  rain  from  the  northward  in  north  latitudes,  but 
from  the  southward  in  south  latitudes. 

A  rise,  with  southerly  winds,  indicates  fine  weather  in  north 
latitudes,  the  conditions  being  reversed  in  south  latitudes. 

A  steady  barometer,  with  dry  and  seasonable  tempera- 
ture, indicates  a  continuance  of  very  fine  weather. 

A  rapid  fall  indicates  stormy  weather. 

A  rapid  fall,. with  westerly  winds,  indicates  stormy  weather 
from  the  northward. 

A  fall,  with  a  northerly  wind,  indicates  stormy  weather, 
with  rain  in  summer  and  snow  in  winter. 


284  WIND  AXD  WEATHER 

A  fall,  with  increased  moisture  in  the  air  and  the  tempera- 
ture rising,  indicates  wind  and  rain  from  the  southward. 

A  fall,  with  dry  air  and  cold  increasing,  in  winter,  indicates 
snow. 

A  fall,  after  very  calm  and  warm  weather,  indicates  rain 
with  squally  weather. 

All  indications  pertaining  to  the  fall  of  the  aneroid  apply 
to  northern  latitudes;  in  southern  latitudes,  wind  directions 
are  reversed. 


HURRICANES 

Cyclones,  or  hurricanes,  have  a  rotary  motion  around  a 
center,  or  focus,  and  a  progressive,  or  for^vard,  motion. 
The  peculiarity  of  the  rotarj'  motion  is  that  in  each  hemis- 
phere it  invariably  occurs  in  different  directions.  Thus,  in 
the  northern  hemisphere,  the  rotation  is  contrary  to  the 
motion  of  the  hands  of  a  watch,  that  is,  from  right  to  left; 
in  the  southern  hemisphere,  the  rotation  is  with  the  hands 
of  a  watch,  that  is,  from  left  to  right.  From  the  rotary  motion 
of  cyclones,  it  is  evident  that  the  wind  in  the  front  and 
rear  of  the  storm  must  be  in  a  direction  perpendicular  to 
the  line  of  progression  a  6,  as  shown  in  (x)  of  the  appended 
diagram,  or  nearly  so;  in  other  words,  if  the  cyclone  is  moving 
in  a  north  north-easterly  direction,  the  wind  in  its  front 
should  be  about  east  southeast  and  in  its  rear  about  west 
northwest.  From  this,  an  important  conclusion  may  be 
drawn,  namely,  that  if  we  assume  the  area  of  the  cyclone  to 
be  divided  into  two  equal  parts  by  the  line  of  progression 
a  b,  and  that  another  line  e  d  is  drawn  through  the  center  c 
perpendicular  to  ab,  the  front  quadrant  bed,  in  which  the 
wind  blows  toward  the  line  of  progression,  or  track  of  center, 
is  the  most  dangerous  part  of  the  cyclone,  with  the  exception 
of  the  center  itself.  The  rear  quadrant  a  c  d  may  also  be 
considered  as  dangerous,  because  the  direction  of  the  wind 
will  tend  to  carry  the  vessel  that  may  happen  to  be  there 
into  the  front  quadrant  and  thence  into  the  path  of  the 
center.  These  two  quadrants,  or  the  semicircle  a  d  b,  are 
therefore  known  as  the  dangerous  semicircle,  and  the  other 


WIND  AND  WEATHER 


285v 


286  WIND  AND  WEATHER 

half  aeh  a.s  the  navigable  semicircle,  since  the  wind  in  the 
latter  will  blow  away  from  in  front  of  the  storm  center. 

These  semicircles  change  sides  when  the  hemisphere  is 
changed,  the  dangerous  semicircle  always  being  to  the  right 
of  the  line  of  progression  in  northern  latitudes  and  to  the 
left  in  southern  latitudes. 

From  the  foregoing  conclusions,  rules  have  been  drawn  up 
for  the  use  of  navigators  to  enable  them  to  determine  on 
which  tack  a  ship  should  be  laid-to  when  confronted  with  a 
storm  of  cyclonic  character,  the  object  of  these  rules  being 
to  prevent  the  wind  veering  by  the  ship's  head  and  to  insure 
its  veering  or  shifting  constantly  farther  aft  so  that  she  may 
be  constantly  "coming  up"  to  the  wind,  whereas  in  the 
former  case  she  would  be  "breaking  off"  from  the  wind,  and, 
-even  with  sails  set,  would,  in  so  violent  a  gale,  be  in  danger 
of  gathering  stemboard. 

SUGGESTIONS  FOR  THE  HANDLING  OF  SHIPS  IN  OR 
NEAR   CYCLONES 

As  to  the  handling  of  ships  in  or  near  a  cyclone,  one  should 
bear  in  mind  that  the  safety  of  his  vessel  will  depend  to 
a  great  extent  on  his  good  judgment  as  well  as  on  his  knowl- 
edge of  the  nature  and  peculiarities  of  revolving  storms. 
All  positive  rules  are,  of  course,  more  or  less  defective,  and 
if  blindly  carried  out  may  prove  very  dangerous;  they  are, 
nevertheless,  of  great  value  when  judiciously  used  in  com- 
bination with  a  good  judgment  of  prevailing  circumstances. 

The  first  thing  for  a  navigator  to  do  when  he  has  good 
reason  to  believe  that  a  hurricane  is  approaching  is  to  find 
the  bearing  of  its  center,  and  then  to  shape  his  course  so  as 
to  avoid  it. 

The  early  indications  of  an  approaching  hurricane  are  as 
follows:  Barometer  above  the  normal,  with  cool,  very  clear, 
pleasant  weather;  a  long,  low  ocean  swell  from  the  direction 
of  the  distant  storm;  light,  feathery,  cirrus  clouds,  radiating 
from  a  point  on  the  horizon  where  a  whitish  arc  indicates 
the  bearing  of  the  center.  Later  indications  are  a  falling 
barometer;  halos  about  the  sun  and  moon;  increasing  ocean 
swell;  hot,  moist  weather  with  light,  variable  winds;  deep-red 


WIND  AND  WEATHER  287 

and  violet  tints  at  dawn  and  sunset;  a  heavy  mountainou 
cloud  bank  on  the  distant  horizon;  barometer  falling  rapidly, 
with  passing  rain  squalls.  The  most  timely  and  trusty 
indication  of  a  cyclone  is  often  the  rise  of  the  thermometer 
in  connection  with  a  reversal  of  the  normal  wind.  Thus, 
in  the  regions  of  the  trade  winds,  a  brisk  westerly  wind 
suddenly  springing  up  should  at  once  arouse  suspicion, 
particularly  in  the  hurricane  season.  Equally  suspicious  is 
a  strong  easterly  wind  suddenly  succeeding  the  normal 
westerly  winds  prevailing  between  40°  and  45°  N  on  the 
routes  between  the  United  States  and  Europe.  Scarcely  any- 
thing, except  an  approaching  area  of  low  atmospheric  pres- 
sure, can  be  supposed  to  cause  the  sudden  change  of  the 
East  Indian  monsoon  in  August  and  September.  A  cautious 
navigator,  therefore,  may,  by  attending  to  the  abnormal  and 
sudden  change  of  wind  direction,  foresee  that  he  is  in  front 
of  a  revolving  gale,  though  his  barometer  remains  high,  the 
sea  smooth,  and  none  of  the  usual  signs  of  hurricanes  can  be 
distinguished  overhead. 

To  Find  the  Bearing  of  the  Center. — Being  convinced  that 
the  approaching  storm  is  of  a  cyclonic  character,  the  bear- 
ing of  its  center  is  determined.  This  is  done  b^^  facing  the 
wind,  in  which  position  the  center  may  be  assumed  to  bear 
10  or  11  points  to  the  observer's  right  in  northern  latitudes 
and  10  or  11  points  to  the  left  in  southern  latitudes.  If, 
however,  the  ship  is  well  within  the  storm  area,  and  the 
barometer  is  falling  steadily,  the  bearing  of  the  center  may 
be  less  than  10  points;  and  if  the  barometer  has  fallen  as- 
much  as  §  in.,  the  bearing  may  be  considered  as  8  points. 

To  Determine  Position  of  Ship  in  Relation  to  Storm  Track. 
Having  the  approximate  bearing  of  the  storm  center,  the 
next  thing  to  do  is  to  find  the  position  of  the  ship  in  relation 
to  the  track,  or  line  of  progression,  of  the  storm.  This  can 
be  determined  by  observing  the  shifting,  or  veering,  of  the 
wind.  In  the  northern  hemisphere,  if  the  wind  shifts  to 
the  right,  the  ship  is  to  the  right  of  the  track,  as  at  5",  in 
diagram  (x)  of  the  preceding  illustration,  or  in  the  dangerous, 
semicircle;  if  it  shifts  to  the  left,  the  ship  is  to  the  left  of 
the  track,  as  at  Si,  or  in  the  navigable  semicircle. 


:238  WIND  AND  WEATHER 

These  conditions  are  reversed  in  the  southern  hefnisphere. 
There,  if  the  wind  shifts  to  the  right,  the  ship  is  to  the  right 
of  the  track,  as  at  Si,  (y),  or  in  the  navigable  semicircle; 
while,  if  the  wind  shifts  to  the  left,  the  ship  is  at  5  (y), 
or  in  the  dangerous  semicircle  (in  both  cases  the  observer 
is  assumed  to  be  looking  in  the  direction  toward  which  the 
storm  is  advancing).  But  if  the  wind  is  "steady,"  shifting 
but  very  slightly  and  increasing  in  velocity,  it  indicates 
that  the  ship,  whether  in  the  north  or  south  hemisphere,  is 
on  the  track  and  in  front  of  the  center,  as  at  52,  (x)  and  (y) . 

To  Find  Whether  Center  Is  Approaching  or  Receding. 
When  a  ship  is  well  within  the  area  of  a  hurricane  the 
approach  of  the  center  is  indicated  by  a  rapidly  falling 
barometer,  increase  of  wind,  heavy  squalls,  intense  light- 
ning and  rain,  heavy  and  confused  sea,  continued  shifting 
of  the  wind,  except  when  on  the  track  of  the  center. 

The  receding  of  the  center  is  usually  indicated  by  a  rising 
barometer,  more  steady  wind  decreasing  in  velocity,  weather 
clearing,  but  sea  very  confused  and  dangerous. 

Brief  Rules  for  Action  to  Avoid  Center. — Having  deter- 
mined the  bearing  of  the  storm  center  and  the  position  of 
the  ship  in  reference  to  the  progressive  motion  of  the  storm, 
the  following  rules  for  avoiding  the  storm  center  should  be 
adhered  to  as  far  as  circumstances  will  permit: 

Northern  Hemisphere. — If  on  the  track  of  the  storm  center 
and  in  front  of  the  advancing  storm,  run  or  steam  before 
the  wind;  keep  a  steady  course  until  the  wind  shifts  well 
on  starboard  quarter.  Then,  if  obliged  to  lie-to,  do  so  on 
the  port  tack. 

If  in  the  dangerous  semicircle,  steam  or  run  off  with  the 
wind  on  starboard  quarter;  if  obliged  to  lie-to,  do  so  on  the 
starboard  tack. 

If  in  the  navigable  semicircle,  steam  or  run  off  with  the 
wind  on  starboard  quarter;  if  obliged  to  lie-to,  do  so  on 
the  port  tack. 

Southern  Hemisphere. — If  directly  in  front  of  the  advancing 
storm  center,  run  or  steam  before  the  wind;  keep  a  steady 
■course  until  the  wind  gradually  shifts  around  to  the  port  quar- 
ter.   Then,  if  obliged  to  lie-to,  do  so  on  the  starboard  tack. 


WIND  AND  WEATHER  289 

If  in  the  dangerous  semicircle,  steam  or  run  off  with  the 
wind  on  the  port  quarter;  if  obliged  to  lie-to,  do  so  on  the 
port  tack. 

If  in  the  navigable  semicircle,  steam  or  run  off  with  the 
wind  on  the  port  quarter;  if  obliged  to  lie-to,  do  so  on  the 
starboard  tack. 

Vessels,  especially  steamships,  sometimes  overtake  hurri- 
canes because  their  speed  is  greater  than  the  progression  of 
the  storm  center.  In  such  cases,  it  is  obvious  that  the  ship's 
course  should  be  altered  so  as  not  to  approach  the  center. 

The  Storm  Center. — The  foregoing  rules  apply  to  cases 
when  hurricanes  are  encountered  in  open  sea.  If,  however, 
the  vessel  is  unable,  from  want  of  sea  room,  to  perform  the 
necessarj^  maneuvers,  her  position  becomes  one  of  great 
danger.  Every  precaution  should  then  be  taken  to  prepare 
for  the  passage  of  the  storm  center  over  the  ship.  In 
entering  the  center,  which  may  be  several  miles  in  diameter, 
the  wind  suddenly  ceases  and  glimpses  of  clear  sky  can  be 
seen,  now  and  then  interrupted  by  puffy  squalls.  The  sea 
is  enormous  and  very  dangerous,  apparently  coming  from 
all  directions  of  the  compass.  After  the  center  has  passed 
over,  the  ship  is  again  struck  by  a  gale  of  renewed  energy 
and  hurricane  force,  but  from  the  opposite  direction.  This 
constitutes  one  of  the  most  critical  dangers  known  to 
seamen.  Apparently,  the  best  thing  to  do  when  caught  in 
the  center  of  a  hurricane  is  to  try  to  get  the  vessel  in  such  a 
position  as  to  best  meet  the  opposite  wind,  which  may  be 
expected  to  burst  forth  very  quickly  and  violently,  and 
thereby  prevent  the  ship  gathering  sternboard,  or  drifting 
backwards  in  a  helpless  position  with  enormous  seas  break- 
ing over  her.  Only  strongly  built  vessels  are  able  to  with- 
stand the  heavy  strain  they  are  subjected  to  under  such  cir- 
cumstances, and  many  ships  whose  names  now  figure  on 
the  list  of  "missing"  in  all  probability  met  their  fate  in 
the  center  of  a  revolving  storm. 

The  t3rphoon  of  the  Western  Pacific  Ocean  is,  in  many 
respects,  the  counterpart  of  the  West  Indian  hurricane  of 
the  Atlantic.  Both  classes  of  storms  have  their  origin  in 
the  vicinity  of  tropical  groups  of  islands,  and  .under  similar 


290  WIXD  AXD  WEATHER 

barometric  conditions;  both  undergo  the  same  slow  develop- 
ment and  exhibit  a  similar  tendency  to  recurve  on  reaching 
the  higher  latitudes. 

The  first  barometric  indication  of  the  approach  of  a 
typhoon  is  the  disturbance  of  the  daily  fluctuations  of  the 
mercurial  column.  In  the  low  latitudes  where  typhoons 
originate,  a  good  mercurial  barometer  during  settled  weather 
should  show  a  decided  maximum  about  10  a.  m.,  the  reading 
at  that  hour  standing  between  29.85  and  29.95  in.  (758.2  to 
760.7  millimeters),  while  about  4  p.  M.  there  should  be  a 
corresponding  minimum,  the  reading  at  that  hour  being 
about  tV  in.  (2.5  millimeters)  less  than  at  10  a.  m.  The 
same  thing  is  repeated  at  10  P.  M.  and  at  4  A.  m.  If  the  fore- 
noon maximum  is  appreciably  below  29.85  in.,  or  if  the 
descent  between  this  and  the  afternoon  minimum  is  markedly 
greater  than  tV  in.,  the  weather  should  be  watched  with 
great  care.  Several  successive  days  of  light,  variable  winds 
and  calms;  a  period  of  hot,  sultry  weather;  increasing 
moisture  of  the  atmosphere;  increasing  amount  of  cloud  and 
an  ominous  heaving  of  the  sea,  are  all  conditions  forerunning 
the  occurrence  of  the  typhoon. 

The  average  tracks  of  the  various  classes  of  typhoons, 
together  with  the  frequency  and  the  season  of  appearance 
of  each  class,  are  to  be  found  on  Pilot  Charts  of  the  Pacific 
Ocean.  For  a  more  complete  account  of  typhoons,  consult 
the  North  Pacific  Pilot  Chart  for  July,  1898. 

Remarks. — It  must  be  borne  in  mind  that  although  the 
region  and  season  of  the  year  would  render  the  navigator 
very  cautious,  yet  every  strong  wind  or  gale  met  with, 
particularly  in  the  tropical  regions,  must  not  be  treated  as 
a  cyclone.  When  there  is  reason  to  stxspect  the  advance  of 
a  cyclonic  storm,  the  safest  proceeding  is  to  lie-to  and 
carefully  watch  the  barometer,  weather  indications,  and 
shiftings  of  the  wind.  A  decided  drop  of  the  atmospheric 
pressure  of  at  least  i  in.,  together  with  marked  shiftings  of 
the  wind,  should  be  experienced  before  the  storm  can  be 
regarded  as  cyclonic. 

Meteorological  Observations  at  Sea. — The  United  States 
Hydrographic  Office  is  conducting  an  extensive  system  of 


WIND  AXD  WEATHER  291 

ocean  meteorological  observations.  It  seeks  the  cooperation 
of  all  navigators,  requesting  them  to  take  one  observation 
every  day  at  a  prescribed  moment,  which  is  simultaneous 
for  every  part  of  the  globe.  These  simultaneous  observa- 
tions are  charted  and  published  by  the  Hydrographic  Office 
at  Washington  on  its  Monthly  Pilot  Charts  and  Hydro- 
graphic  Bulletins.  By  entering  into  this  arrangement  and 
taking  part  in  the  observational  work,  every  seaman  may 
contribute  materially  to  this  scientific  enterprise  and  further 
the  elucidation  of  the  law  of  storms,  as  well  as  secure  for 
his  own  use  a  large  supply  of  valuable  meteorological  infor- 
mation. 

When  about  to  sail,  the  master  or  navigating  officer  of 
a  vessel  should  call  at  the  local  branch  hydrographic  office 
and  request  the  officer  in  charge  to  furnish  him  with  the 
latest  information  in  the  shape  of  Lists  of  Lighls,  Lists  of 
Beacons,  Buoys,  and  Daymarks,  Notices  to  Mariner?, 
Hydrographic  Bulletins,  and  Pilot  Charts.  All  these  pub- 
lications are  furnished  free  to  masters  who  can  satisfactorily 
show  that  they  are  voluntary  weather  observers  for  the 
United  States  Hydrographic  Office,  or  that  they  are  willing 
to  become  such.  He  should  also  request  a  supply  of  blank 
weather  reports  and  envelopes  sufficient  to  last  until  his 
return  to  a  United  States  port ;  also  of  cards  for  barometer 
comparisons,  with  instructions  as  to  the  manner  of  making 
these  comparisons,  which  are  given  in  Hydrographic  Office 
publication  No.  119.  The  comparison  cards  should  be 
filled  out  while  the  vessel  is  lying  in  port  and  should  be 
mailed  before  sailing.  They  require  (if  mailed  in  a  United 
States  port)  neither  envelope  nor  postage. 

For  the  convenience  of  those  masters  who  rarely  visit  an 
American  port,  a  limited  supply  of  blanks,  pilot  charts,  etc. 
is  maintained  at  the  U.  S.  consulate  in  each  of  the  more 
important  shipping  centers  abroad.  A  list  of  those  con- 
sulates at  which  this  is  the  case  is  published  on  the  monthly 
pilot  charts. 

Having  arrived  at  his  destination,  the  forms  containing  the 
observations  recorded  during  the  voyage  should  be  enclosed 
in  one  or  more  of  the  envelopes  furnished  for  that  purpose. 


292  WIND  AND  WEATHER 

If  in  a  foreign  port,  this  envelope  should  be  addressed  to 
the  United  States  Hydrographic  Office,  Navy  Department, 
Washington,  D.  C,  and  handed  to  the  United  States  consul, 
who  is  under  instructions  from  the  Secretary  of  State  to 
forward  it  with  his  official  mail,  free  of  all'  expense.  If 
mailed  at  any  port  outside  of  the  United  States,  postage 
must  be  prepaid  at  letter  rates. 

In  any  United  States  port,  the  package  should  be  addressed 
to  the  nearest  branch  hydrographic  office  and  mailed.  The 
franked  envelope  does  not  require  any  postage  when  mailed 
within  the  United  States,  Hawaii,  the  Philippine  Islands, 
or  Porto  Rico. 

The  forms  should  be  returned  promptly  at  the  close  of 
each  voyage,  or  even  at  the  first  port  of  call.  They  should 
not  be  held  until  the  return  of  the  vessel  to  the  United 
States. 

.  On  the  receipt  of  the  completed  forms,  either  at  the 
United  States  Hydrographic  Office  or  at  any  of  its  branches, 
a  letter  of  acknowledgment  is  at  once  addressed  to  the 
master  of  the  vessel,  thanking  him  and  the  officer  charged 
with  the  duty  of  taking  the  observations  for  their  services, 
and  replying  to  any  inquiry  or  request  that  the  master  or 
the  observer  may  have  made  on  the  pages  alloted  to  that 
purpose.  These  letters  of  acknowledgment  should  in  all 
cases  be  preserved,  as  they  may  prove  of  value  in  identify- 
ing the  bearer  as  an  observer  at  the  several  branch  hydro- 
graphic  offices,  and  as  such  entitled  to  the  various  official 
publications. 

The  list  of  Atlantic  and  Pacific  coast  ports  at  which 
branch  hydrographic  offices  are  established  is  at  present 
(March,  190-i)  as  follows:  Boston,  custom  house;  New 
York,  Maritime  Exchange;  Philadelphia,  Bourse  Building; 
Baltimore,  custom  house;  Norfolk,  custom  house;  Savannah, 
custom  house;  New  Orleans,  custom  house;  Galveston,  Levy 
Building;  San  Francisco,  Merchants'  Exchange;  Portland, 
Ore.,  custom  house;  Port  Townsend,  custom  house. 


CODE  FLAGS  AND  PENNANTS 
INTERNATIONAL  CODE  OF  SIGNALS 
IHstinguishing 


SIGNALS  293 

SIGNALS 


INTERNATIONAL  CODE  OF  SIGNALS 

The  new  International  Code  of  Signals,  shown  in  the 
attached  figure,  and  which  came  into  use  on  January  1,  1901, 
consists  of  26  flags;  viz.,  2  burgees,  5  pennants,  and  19  square 
flags,  besides  the  code  flag,  which  is  used  also  as  the  ans%ver- 
ing  pennant.  Its  object  is  to  supply  means  of  intercourse 
between  ships  meeting  at  sea,  as  well  as  between  ships  and 
established  signal  stations  on  land.  It  has  been  adopted 
by  all  the  important  maritime  powers  of  the  world,  and  the 
interpretation  of  the  several  thousand  different  signals 
composing  the  system  are  translated  into  the  language  of 
each  nation.  All  ships,  therefore,  when  meeting  at  sea 
are  enabled  to  communicate  with  one  another,  no  matter 
if  one  is  an  American  and  the  other  a  Greek,  or  whether 
the  commander  of  one  vessel  is  able  to  master  the  language 
of  the  other  in  a  verbal  conversation. 

Arrangement  of  Code  Book. — The  new  Code  Book  pub- 
lished by  the  Bureau  of  Equipment,  U.  S.  Navy  Department, 
is  divided  into  three  parts,  as  follows: 

Part  I  contains  instructions  on  how  to  make  and  how  to 
answer  a  signal,  accompanied  by  suitable  examples;  then 
comes  an  alphabetical  spelling  table,  numeral  signals,  urgent 
and  important  signals,  compass  signals,  signals  appertaining 
to  money  and  all  kinds  of  measurements,  signals  relating  to 
latitude,  longitude,  time,  barometer,  thermometer,  phrase 
signals  formed  with  auxiliary  verbs,  and  geographical  signals. 
Of  these  signals,  only  those  coming  under  the  heading  of 
"urgent  and  important"  are  made  with  2  flags  in  a  hoist; 
all  others  are  made  with  3  flags,  with  the  exception  of 
geographical  signals,  which  are  made  with  4  flags  in  a  hoist. 

Part  II  contains  an  index  of  general  vocabulary  signals, 
and  a  second  list  of  geographical  signals,  in  which  the  names, 
of  places  are  alphabetically  arranged.  The  vocabulary  sig- 
nals are  with  few  exceptions  3-flag  signals. 


2»4  SIGNALS 

Part  III  contains  a  list  of  storm-warning,  display,  life- 
saving,  and  time-signal  stations  of  the  United  States;  also 
Lloyd's  signal  stations  of  the  world,  and  American,  English, 
and  French  semaphore,  distance,  and  wigwag  codes. 

Since  each  of  the  26  letters  of  the  alphabet  is  represented 
by  a  flag,  it  is  evident  that  any  word  can  be  spelled  by  this 
system,  and  if  the  word  to  be  spelled  consists  of  more  than 
4  letters,  two  or  more  hoists  must  be  used,  as  no  hoist  is 
to  contain  more  than  4  flags.  Explanations  and  instruc- 
tions on  this  subject  are  to  be  found  on  pages  13  and  14  of 
the  code  book. 

CHARACTER  OF  SIGNALS  AS  INDICATED  BY  THE 
NUMBER  OF  FLAGS  IN  A  HOIST 

One-Flag  Signal. — The  meaning  of  flags  and  pennants 
hoisted  singly  and  with  the  code  flag  is  found  on  pages  7 
and  35  of  the  code  book. 

Two-Flag  Signals. — Signals  composed  of  2  flags  are  urgent 
or  important  signals;  they  run  from  A  B  to  Z  Y. 

Three-Flag  Signals. — Signals  composed  of  3  flags  are 
either  Compass,  measurement,  auxiliary  phrases,  or  general 
vocabulary  signals.  Compass  signals  run  from  A  B  C  to 
AST;  signals  relating  to  money,  from  A  S  U  to  AV  J; 
and  those  relating  to  weight  and  measures,  from  A  V  K 
to  B  C  N.  Three-flag  signals  having  the  code  flag  upper- 
most relate  to  latitude,  longitude,  time,  barometer,  or  to 
the  thermometer. 

Four-Flag  Signals. — Signals  composed  of  4  flags  are  either 
geographical  or  alphabetical  signals.  All  geographical  sig- 
nals begin  with  the  letter  A  or  B  and  run  from  A  B  C  D  to 
B  F  A  U.     Alphabetical  signals  commence  with  the  letter  C. 

SELECTED  SIGNALS 

The  following  is  a  selection  of  signals  for  the  use  of  vessels 
meeting  at  sea,  or  vessels  in  sight  of  signal  stations.  By 
committing  these  signals  to  memory,  much  delay  in  search- 
ing for  them  in  the  code  book  is  obviated. 


SIGNALS  295 

Signals  Meaning 

E  C— What  ship  is  that  ? 
S  I — Where  are  you  from  ? 
S  H — Where  are  you  bound  ? 
5  G — When  did  you  sail  ? 
U  B — Do  you  wish  to  be  reported? 
U  D — Report  me,  by  telegraph,  to  Lloyd's. 
U  R  Z— Report  me  all  well. 

U  £— Report  me,  by  telegraph,  to  owners. 
U  F — Report  me,  by  telegraph,  to  "Shipping  Gazette." 
U  G — Report  me  to  Lloyd's  (either  by  post  or  tele- 
graph) . 
U  I — Report  me  to  "New  York  Herald"  office,  London. 
U  J — Report  me  to  "New  York  Herald"  office.  New  York. 

V  J — I  wish  to  signal ;  will  you  come  within  easy  signal 

distance  ? 
VM — Cannot    distinguish  your  flags;   come  nearer,  or, 
make  distant  signals. 

V  I — Repeat  your  signal. 

5  W — I  wish  to  obtain  orders  from  my  owner — (name) . 

T  D — There  are  no  orders  for  you  here. 

T  E — Wait  for  orders. 

Q  U — Will  you  forward  my  letters? 

Q  R- — Send  your  letters. 

Y  E — Want  assistance. 

Y  L — Want  immediate  medical  assistance. 

N  C — In  distress;  want  immediate  assistance. 

D  C — We  are  coming  to  your  assistance. 

C  X — No  assistance  can  be  rendered;  do  the  best  you 

can  for  yourselves. 
F  //—Send  a  boat. 
E  U — Boat  is  going  to  you. 
E  X — Cannot  send  boat. 
B  O — Have  lost  all  my  boats. 

I — Come  nearer.     Stop,  or  heave  to.    I  have  some- 

--  f  thing  important  to  communicate, 

over  H] 

I  F — Cannot  stop  to  have  any  communications. 

R  Z — Where  am  I  ?     What  is  my  present  position  ? 


296  SIGNALS 

Q  I  B — What  is  your  latitude  brought  up  to  the  present 

moment  ? 
Q  Z  K — What  is  your  longitude  brought  up  to  the  present 

moment  ? 
Q  H  W — My  latitude  is    .    .    . 
Q  Z  F — My  longitude  by  chronometer  is    .    .    . 
XN — Will  you  show  me  your  Greenwich  time? 
G  U — Will  you  give  me  a  comparison?     Wish  to  get  a 
rate  for  my  chronometer. 
I Q  H — I  have  no  chronometer. 
G  Q — My  chronometer  has  run  down. 
M  R — Have  broken  main  shaft. 
M  W — One  screw  disabled;  can  work  the  other. 
MQ — Engines  completely  disabled. 
M  X — Passed  disabled  steamer  at     .     .     . 
H  M — Vessel    seiiously    damaged;    wish    to    transfer 

passengers. 
G  Y — Can  you  spare  me  coal? 
H  C — Indicate  nearest  place  I  can  get  coal. 
B  I — Damaged  rudder,  cannot  steer. 
J  D — You  are  standing  into  danger. 
S  A — Are  there  any  men  of  war  about? 
X  O — Beware  of  torpedo  boats. 
X  P — Beware   of   torpedoes;   channel    (or  fairway)   is 

mined, 
y  P — Want  a  tug  (if  more  than  one,  number  to  follow). 

Y  O — Want  provisions  immediately. 

Y  R — Want  water  immediately. 

C",  or  code  flag  over  C — Yes,  or  affirmative, 
D,  or  code  flag  over  D — No,  or  negative. 

DISTANT  SIGNALS 
Distant  Signals  are  used  when,  in  consequence  of  distance 
or  the  state  of  the  atmosphere,  it  is  impossible  to  distinguish 
the  colors  of  the  flags  of  the  International  Code,  and,  there- 
fore, to  read  a  signal  made  by  those  flags;  they  also  provide 
an  alternative  system  of  making  the  signals  in  the  Code, 
which  can  be  adopted  when  the  system  of  flags  cannot  be 
employed.     Three  methods  of  making  distant  signals  are 


SIGNALS 


297 


used:  (1)  by  cones,  balls,  and  drums;  (2)  by  balls,  square 
flags,  pennants,  and  wafts;  (3)  by  the  fixed  coast  sema- 
phore. 

In  calms,  or  when  the  wind  is  blowing  toward  or  from  the 
observer,  it  is  often  difficult  to  distinguish  with  certainty 
between  a  square  flag,  pennant,  and  waft,  and  as  flags 
when  hanging  up  and  down  may  hide  one  of  the  balls  and 
so  prevent  the  signal  being  understood,  the  system  of  cones, 
balls,  and  drums  is  preferable  to  that  of  flags,  pennants, 
and  wafts. 

The  following  special  distant  signals  are  made  by  a  single 
hoist  followed  by  the  "Stop"  signal.  They  are  arranged 
numerically  for  reading  off  the  signal. 


SPECIAL  DISTANT  SIGNALS 


2 — "Preparative," 
"answering,"  or 
"stop,"  after  each 
complete  signal. 


1.  2 — Aground;  want 
immediate  assist- 
ance. 


1 — Fire  or  Leak; 
want  immediate 
assistance. 


!> 


2 — A  n  n  u  1 
whole  signal. 


.3 — You  are  run- 
ning into  danger, 
or.  Your  course  is 
dangerous. 


2,  4 — Want  water  im- 
mediately. 


3,  2  — Short  of  provi- 
sions; starving. 


4,  2 — Annul  the  last 
hoist;  I  will  repeat 

it. 


1,1,  2 — I  am  on  fire. 


1,2, 1 — I  am  aground 


2,  2— Yes,    or  af- 
firmative. 


2,  3, — No.  or  neg- 
ative. 


298 


SIGNALS 


h 
N 


1.2.4— Send  lifeboat. 


1,3.  2 — Do  not  aban- 
don the  vessel. 


1,4,  2 — Do  not  aban- 
don the  vessel  until 
the  tide  has  ebbed. 


2,  1,  1 — Assistance  is 
coming. 


2,    1,    2 — Landing    is 
impossible. 


2,   1,  3 — Bar   or   en- 
trance is  dangerous. 


2,  1,  4— Ship  dis- 
abled; will  you  as- 
sist '  me  into  port  ? 


2,  2.  1— Want  a  pilot. 


2,  2,  3— Want  a  tug; 
can  I  obtain  one? 

2,  2,  4— Want  the 
name  of  ship  (or  sig- 
nal station)in  sight, 
or,  Show  your  dis- 
tinguishing signal. 


IN 


2,   3.    1 — Show   your 
ensign. 


3,  2 — Have  you  any 
dispatches  (mes- 
sages, orders,  or 
telegrams)  for  me? 

3,  3— Stop,  bring- 
to,  or.  Come  nearer; 
I  have  something 
important  to  com- 
municate. 

3.  4 — Repeat  signal 
or  hoist  it  in  a  more 
conspicuous  posi- 
tion. 

,  4,  1-;— Cannot  dis- 
tinguish your  flags; 
come  nearer  or 
make  distant  sig- 
nals. 

,  4,  2— Weigh,  cut, 
or  slip;  Wait  for 
nothing;  Get  an 
offing. 


2,4.  3 — Cyclone,  hur- 
ricane, or  typhoon 
expected. 


3,  1.  2— Is  war  de- 
clared, or.  Has  war 
commenced? 


3,  2.  1— War  is  de- 
clared, or.  War  has 
commenced. 


3.  2,  2 — Beware  of 
torpedoes;  channel 
is  mined. 


SIGXALS  2G9 

3,  4,  2 — Keep  a  good 

o      o      o     -D^^r^^^    «f  o  lookout,  as  it  is  re- 

'•toVd^Wr    °'  k        P-^^<i     that     ene- 

twipciiij  uudi-o.  11^         my  s  men  ot  war  are 


going     about     dis- 
guised as  merchant 
3.  2. '4— Enemy  is  in  ships. 


sight. 


3,  3,  2 — Enemy  is 
closing  with  you, 
or,  You  are  closing 
with  the  enemy. 


4,    1,   2 — Proceed   on 
your  voyage. 


The  following  distant  signals,  made  with  flag  and  ball,  or 
pennant  and  ball,  have  the  special  signification,  indicated 
beneath  them.     Jupiter,  Fla.    [See  following  page]. 


\um  You    are    running  P^^ 

[W^lf  into  danger.                    V 

jfv  Fire,  or  leak;  want  Ir^^^ 

^^^^^  immediate  assist-             T' 

1    ~  ^"^^-  i   k 


Short  of  provisions 
— starving. 


Aground;  want  im- 
mediate assist- 
ance. 


LIST  OF  WEATHER  BUREAU  STATIONS  ON  THE  UNITED 
STATES  SEACOAST  TELEGRAPHIC  LINES 

Atlantic  Coast. — Nantucket,  Mass.;  Narragansett  Pier, 
R.  I.;  Block  Island,  R.  I.;  Norfolk,  Va.;  Cape  Henry,  Va.; 
Currituck  Inlet,  N.  C;  Kitty  Hawk,  N.  C;  Hatteras,  N.  C; 
Sand  Key,  Fla; 

Pacific  Coast. — Tatoosh  Island,  Wash.;  Neah  Bay,  Wash.; 
East  Clallam.  Wash.;  Twin  Rivers,  Wash.;  Port  Crescent, 
Wash.;  North  Head,  Wash.;  Point  Reyes  Light,  Cal.;  San 
Francisco,    Cal.;    Southeast    Farallone,    Cal.;    Jupiter,    Fla. 

Lake  Huron. — Thunder  Bay  Island,  Mich.;  Middle  Island, 
Mich.;  Alpena,  Mich. 

Of  these  stations,  the  following  are  equipped  with  Inter- 
national Code  signals,  and  communication  can  be  had  there- 
with for  the  purpose  of  obtaining   information  concerning 


300  SIGXALS 

the  approach  of  storms,  weather  conditions  in  general,  and 
for  the  purpose  of  sending  telegrams  to  points  on  commercial 
lines: 

Nantucket,  Mass.:  Block  Island,  R.  I.;  Cape  Henry,  Va.; 
Hatteras,  N.  C;  Kitty  Hawk,  X.  C;  Sand  Key,  Fla.; 
Jupiter,  Fla.;  Tatoosh  Island,  Wash.;  Neah  Bay,  Wash.; 
Point  Reyes  Light,  Cal.;  Southeast  Farallone,  Cal. 

Any  message  signaled  by  the  International  Code,  as 
adopted  or  used  by  England,  France,  America,  Denmark, 
Holland,  Sweden,  Norway,  Russia,  Greece,  Italy,  Germany, 
Austria,  Spain,  Portugal,  and  Brazil,  received  at  these 
telegraphic  signal  stations,  will  be  transmitted  and  delivered 
to  the  address  on  payment  at  the  receiving  station  of  the 
telegraphic  charge.  All  messages  received  from  or  addressed 
to  the  War,  Navy,  Treasury,  State,  Interior,  or  other  official 
department  at  Washington,  are  telegraphed  without  charge 
over  the  Weather  Bureau  lines. 

DISTRESS  SIGNALS 

When  a  vessel  is  in  distress,  and  requires  assistance  from 
other  vessels  or  from  the  shore,  the  following  are  the  signals 
to  be  used  by  her,  either  together  or  separately: 

Daytime. — 1.  A  gun  or  other  explosive  signal  fired  at 
intervals  of  about  a  minute. 

2.  The  International  Code  signal  of  distress  indicated 
by  A^C. 

3.  The  distant  signal,  consisting  of  a  square  flag,  having 
either  above  or  below  it  a  ball  or  anything  resembling  a  ball. 

4.  The  distant  signal,  consisting  of  a  cone  pointing 
upwards,  having  either  above  or  below  it  a  ball  or  anything 
resembling  a  ball. 

5.  A  continuous  sounding  with  any  fog-signal  apparatus. 
At  Night. — 1.     A  gun  or  other  explosive  signal  fired  at 

intervals  of  about  a  minute. 

2.  Flames  on  the  vessel  (as  from  a  burning  tar  barrel 
oil  barrel,  etc.). 

3.  Rockets  or  shells,  throwing  stars  of  any  color  or 
description,  fired  one  at  a  time  at  short  intervals. 

4.  A  continuous  sounding  with  any  fog-signal  apparatus. 


U.  S,  STORM  SIGNALS 


N.fF:  s.w. 

Winds  Winds 

Flags  8  feet  square. 


N.  E.         S.  E.       Hu  rri  ca  ne" 
Winds        Winds      Signal 

Pennants  5  feet  hoist,  12  feet  fly. 


U.  S.  WEATHER-BUREAU  SIGNALS 


Clear  or 
Fair  WeafAer 


11 


3 

y 


^Locatliai/v 
II  orS/iow 


When  number  4  is  placed  above  number  1,  2,  or  S  it  indicates 
warmer;  when  below,  colder;  when  not  displayed,  the  tempera- 
ture ts  expected  to  remain  about  stationary.  Number  6  is  used 
also  to  indicate  anticipated  frosts. 


SIGMALS  301 

Xot  Under  Control. — A  vessel  temporarily  disabled  at  sea, 
through  the  breaking  down  of  her  engines,  etc.,  but  not 
requiring  assistance,  shovild,  in  daytime,  hoist  two  black 
balls,  or  shapes  resembling  balls,  one  above  the  other,  and  at 
night  two  red  lights  in  a  similar  position.  Such  signal 
means  *'  I  am  not  under  control,"  and  should  be  kept 
hoisted  until  repairs  are  effected  or  until  the  vessel  is  in  a 
position  to  proceed  on  her  voyage. 

U.  S.  STORM  SIGNALS 

Storm  Warning  Flags.  —  A  red  flag  with  a  black  center 
indicates  that  a  stonn  of  marked  violence  is  expected. 
The  pennants  displayed  with  the  flags  indicate  the  direction 
of  the  wind:  red,  easterly  (from  northeast  to  south);  white, 
westerly  (from  southwest  to  north).  The  pennant  above 
the  flag  indicates  that  the  wind  is  expected  to  blow  from 
the  northerly  quadrants;  below,  from  southerly  quadrants. 
By  night,  a  red  light  indicates  easterly  winds,  and  a  -white 
light  above  a  red  light,  westerly  wnnds. 

Hurricane  Warning. — Two  red  flags,  with  black  centers, 
displayed  one  above  the  other,  indicate  the  expected  approach 
of  tropical  hurricanes,  and  also  of  those  extremely  severe 
and  dangerous  storms  that  occasionally  move  across  the 
lakes  and  northern  Atlantic  coast.  Hurricane  warnings  are 
not  displayed  at  night. 

Storm  signals  are  displayed  by  the  United  States  Weather 
Bureau  at  141  stations  situated  along  the  Atlantic  and 
Gulf  coasts,  and  at  27  stations  situated  on  the  Pacific  coast 
of  the  United  States. 

SIGNALS  FOR  PILOT 

The  following  signals,  when  used  or  displayed  together  or 
separately,  shall  be  deemed  to  be  signals  for  a  pilot: 

Daytime. — 1.  The  Jack,  or  other  national  ensign,  usually 
worn  by  merchant  ships,  having  around  it  a  white  border 
one-fifth  the  breadth  of  the  flag,  to  be  hoisted  at  the  foretop. 

2.  The  International  Code  pilot  signal  indicated  by  P  T. 

3.  The  International  Code  flag  S,  with  or  without  the 
code  pennant  over  it. 


S02  SIGNALS 

4.  The  distant  signal  consisting  of  a  cone,  point  upwards, 
having  above  it  two  balls,  or  shapes  resembling  balls. 

At  Night. — 1,  The  pyrotechnic  light,  commonly  known 
as  a  "blue  light,"  every  15  min. 

2.  A  bright  white  light,  flashed  or  shown  at  short  or 
frequent  intervals,  just  above  the  bulwarks,  for  about  a 
minute  at  a  time. 

LIFE-SAVING  SIGNALS 

The  following  signals,  recommended  by  the  recent  Inter- 
national Marine  Conference  for  adoption  by  all  institutions 
for  saving  life  from  wrecked  vessels,  have  been  adopted  by 
the  Life-Saving  Service  of  the  United  States: 

1.  Upon  the  discovery  of  a  wreck  by  night,  the  life- 
saving  force  will  bum  a  red  pyrotechnic  light,  or  a  red  rocket, 
to  signify:  "You  are  seen;  assistance  will  be  given  as  soon 
as  possible." 

2.  A  red  flag  waved  on  shore  by  day,  or  a  red  light,  red 
rocket,  or  red  Roman  candle  displayed  at  night,  will  signify: 
"Haul  away." 

3.  A  white  flag  waved  on  shore  by  day,  or  a  white  light 
slowly  swung  back  and  forth,  or  a  white  rocket  or  white 
Roman  candle  fired  by  night,  will  signify:    "Slack  away." 

4.  Two  flags,  a.  white  and  a  red,  waved  at  the  same  time 
on  shore  by  day,  or  two  lights,  a  white  and  a  red,  slowly 
swung  at  the  same  time,  or  a  blue  pyrotechnic  light  burned 
by  night,  will  signify:  "Do  not  attempt  to  land  in  your  own 
boats;  it  is  impossible." 

5.  A  man  on  shore  beckoning  by  day,  or  two  torches 
burning  near  together  by  night,  will  signify:  "This  is  the 
best  place  to  land." 

Any  of  these  signals  may  be  answered  from  the  vessel 
as  follows:  In  the  daytime,  by  waving  a  flag,  a  handker- 
chief, a  hat,  or  even  the  hand;  at  night,  by  firing  a  rocket, 
a  blue  light,  or  a  gun,  or  by  showing  a  light  over  the  ship's 
gunwale  for  a  short  time  and  then  concealing  it. 

NoTB. — It  is  important  that  all  .signals  from  shore  arc  answered  hy  the  ship 
«t  once,  particularly  so  at  niKht.  It  signals  are  not  aiiswereil  within  a  reason- 
*ble  time,  the  life-saving  crew  on  thi;  beach  might  infer  that  the  crew  of  the 
•trandeil  vessel  have  perished,  ami  as  a  consequence  they  may  abandon  their 
etlorts  ut  regcue. 


SIGXALS  303 

USE  OIL  IN  HEAVY  SEA 

Running  before  a  gale,  use  oil  from  bags  at  the  catheads, 
or  from  forward  waste  pipes;  if  yawing  badly  and  threaten- 
ing to  broach-to,  use  oil  forwards  and  abaft  the  beam,  on 
both  sides.  Lying-to,  distribute  oil  from  the  weather  bow. 
With  a  high  beam  sea,  use  oil  bags  at  regular  intervals  along 
the  weather  side.  In  a  heavy  cross  sea,  have  bags  along 
both  sides.  Steaming  into  a  heavy  head  sea,  use  oil  through 
forward  closet  pipes.  There  are  many  other  cases  where  oil 
may  be  used  to  advantage,  such  as  lowering  and  hoisting 
boats,  riding  to  a  sea  anchor,  crossing  rollers  or  surf  on  a 
bar,  and  from  life  boats  and  stranded  vessels.  Thick  and 
heavy  oils  are  the  best.  Mineral  oils  are  not  so  effective 
as  animal  or  vegetable  oil.  Raw  petroleum  has  given 
favorable  results,  but  is  not  so  good  when  refined.  Certain 
oils,  like  cocoanut  oil  and  some  kinds  of  fish  oil,  congeal  in 
cold  weather,  and  are  therefore  useless,  but  may  be  mLxed 
with  mineral  oils  to  advantage.  As  a  general  rule,  probably 
the  best  way  to  use  oil  is  by  filling  the  closet  bowls  forward 
with  oakum  and  oil,  letting  the  oil  drip  out  slowly  through 
the  waste  pipes.  Another  simple  and  easy  way  to  distribute 
oil  is  by  means  of-canvas  bags  about  a  foot  long,  filled  with 
oakum  and  oil,  pierced  with  holes  by  means  of  a  coarse 
sail  needle,  and  held  by  a  lanyard. 


304  NAUTICAL  MEMORANDA 

NAUTICAL  MEMORANDA 

Progress  of   steam   navigation   from  its  inception   to  the 
launching  of  the  'Great  Eastern"  in  1858: 
1707     Denis    Papin    experimented    on    River    Fulda    with 

paddle-wheel  steamboat. 
1736     Jonathan  Hulls  patented  designs  similar  to  modern 

paddle  boat. 

1769  James    Watt    invented     a    double-acting     side-lever 

engine. 

1770  Perier,  in  France,  made  experiments  with  steam  as 

motive  power  for  vessels. 
1785     James  Ramsey,  in  America,   propelled-  a  boat  with 

steam  through  a  stern  pipe. 
17S6     John    Fitch,    in    America,    propelled    a    boat    with 

canoe  paddles  fixed  to  a  moving  beam. 

1787  Robert  Miller,  of  Edinburgh,  experimented  similarly. 

1788  Miller  and  Symington  produced  a  double-hull  stern- 

wheel  steamboat. 
1802     "Charlotte  Dundas,"    the    first    practical   steam    tug, 

designed  by  Symington. 
1804     "Phoenix,"  screw  boat  designed  by  Stephens,  in  New 

York;  first  steamer  to  make  a  sea  voyage. 
1807     "Clermont,"    first    passenger    steamer    continuously 

employed;  designed  and  built  by  Robert  Fulton; 

machinery    built    by    Boulton    and    Watt;    made 

regular    trips    between    New    York    and    Albany; 

speed  about  5  kn. 
1811     "The  Comet,"  first  successful   passenger  steamer  in 

Europe;    built    by    Henry    Bell    and    made    trips 

between  Glasgow  and  Greenock. 
1816     "Witch,"  first  steamboat  built  in  Sweden;  constructed 

by  S.  Owen;  had  an  8-H.   P.  engine  and  a  four- 

bladed  propeller. 

1818  "Rob  Roy,"  first   merchant    steamer   in    the    world, 

built  at  Glasgow. 

1819  "Savannah,"    first    auxiliary    steamer    to    cross    the 

Atlantic;  fitted  with  paddle  wheels;  made  the  trip 
from  Savannah  to  Liverpool  in  22  da. 


XAUTICAL  MEMORAXDA  305 

1821     "Aaron  Manby,"  first  steamer — English  canal  boat — 

built  of  iron. 
1823     City  of  Dublin  Steam  Packet  Co.  was  established. 
1824:     General    Steam    Navigation    Co.    was   established   at 

London. 
1825     "Enterprise"  made  the  first  steam  passage  to  India. 
1825     "William  Fawcett,"  pioneer  steamer  of  the  P.  &  O.  S. 

N.  Co. 
1830     T.  &  J.  Harrison  (Harrison  Line)  established  at  Liver- 
pool. 
1832     "Elburkah,"  iron  steamer,  took  a  private  exploring 

party  up  the  river  Niger. 
1834     Establishment   of   Lloyd's   Register  for   British   and 

foreign  shipping. 

1836  Establishment,    at    Trieste,    of    the    Atistrian    Lloyd 

Steam  Navigation  Co. 

1837  "Francis  B.  Ogden,"  first  successful  screw  tug;  equip- 

ped with  Ericsson's  propeller. 

1838  "Archimedes"  made  the  Dover-Calais  passage  in  less 

than  2  hr. ;  fitted  with  Smith's  propeller. 

1838  "R.  F.  Stockton,"    built  for  a   tug  and  fitted   with 

Ericsson's 'propeller;  sailed  to  America;  first  iron 
vessel  to  cross  the  Atlantic;  first  screw  steamer 
used  in  America. 

1839  "Thames,"  pioneer  steamer  of  the  Royal  Mail  Steam 

Packet  Co. 

1840  "Britannia,"  pioneer  steamer  of  the  Cunard  Line. 
1840     "Chile,"  pioneer  steamer  of  the  Pacific  Steam  Naviga- 
tion Co. 

1845     "Great  Britain,"  first  iron  screw  steamer,  precursor  of 

modem  transatlantic  steamer. 
1845     Wilson  Line,  Thos.  Wilson,  Sons  &  Co.,  Ltd..  estab-, 

lished  at  Hull. 
1847     Pacific  Mail  Steamship  Co.  established  in  America. 
1850     Natal  Line  established  at  London. 
1850     Messageries  Maritimes  de  France  established. 

1850  Inman  (now  American)  Line  established  at  Liverpool. 

1851  "Tiber,"  first  steamer  of  the  Bibby  Line,  established 

in  1821,  at  Liverpool. 


306 


AM  UTICAL  MEMORANDA 


1852  "Forerunner,"  pioneer  steamer  of  the  African  Steam- 

ship Co. 

1853  Union  Steamship  Co.,  now  Union  Castle  Line,  estab- 

lished. 
1853     "Borxissia,"  first  steamer  of  the  Hamburg-American 
Packet  Co.,  established  in  1847. 

UNITED  STATES  NAVY 

{From  Report  of  the  Office  of  Naval  Intelligence,  United  States 
Navy  Department,  1905) 


Type  of  Vessel 

Built 

Tons 

Build- 
ing 

Tons 

Battle  ships,  first  class. 

Other  battle  ships  and 
coast  defense  iron- 
clads  

Armored  cruisers 

Protected  cruisers,  first 
class  (above  6,000 
tons) 

Protected  cruisers,  sec- 
ond class  (3,000  to 
6,000  tons) 

Other  cruisers  and 
scouts  (above  1,000 
tons) . 

12 

12 
2 

2 

15 

23 

137,329 

47,945 
17,415 

14.750 

56,393 

32,773 

13 

8 
3 
4 
2 

192.700 

111,800 

28,800 

12,400 

2,170 

Totals 

66 

306,605 

30 

347,870 

Combined  totals.  .  .  .96  vessels  of  654,475  tons 


NoTK.— Gunboats  and  other  vessels  of  less  than  1,000  T.  are  not  given  in 
the  ta))le,  nor  are  transports,  dispatch  vessels,  converted  merchant  vessels  or 
jachts.  or  olisolete  cruisers.  Vessels  not  begun  are  not  included  in  the  table. 
There  are  Ki  torpetio-boat  destroyers,  27  torpedo  boats,  8  submarine  boats 
belonging  to  the  Navy,  and  6  torpedo  boats  under  construction. 

1854  "Canadian,"  first  steamer  of  the  Allan  Line,  estab- 

lished in  1820. 

1855  Establishment   of  the   British   India  Steam    Naviga- 

tion Co. 

1856  "Tempest,"  first  steamer  of  the  Anchor  Line. 


NAUTICAL  MEMORANDA 


307 


1858  "Bremen."  first  transatlantic  steamer  of  the  Xord- 
deutscher  Lloyd,  established  in  1856. 

1858  "Great  Eastern"  launched  on  the  Thames,  Jan.  31; 
commenced  May  1,  1854. 

MERCHANT  MARINE 

{From  Report  of  the   United  States  Commissioner  of  Naviga- 
tion 1905) 


Districts 

Number 
of  Vessels 

Gross 
Tonnage 

17,040 

42 

2,492 

61 

3,172 

1,466 

2,978,876 

Porto  Rico 

6.180 

Pacific  Coast 

741  825 

32.386 

Great  Lakes     

1,816  511 

222,124 

Total         

24,273 

5  797,902 

Classification  of 

THE  Above 

Type  of  Vessel 

Number 
of  Vessels 

Gross 
Tonnage 

Sailing  vessels 

13,073 

7.727 

703 

2.770 

1,941.878 

Steam  vessels 

Canal  boats 

3,176,874 
79,408 

Barges 

599.742 

Total 

24,273 

5,797,902 

NUMBER  AND  TONNAGE  OF  VESSELS  BUILT  IN  THE 
UNITED  STATES  DURING  THE  YEARS  1868  TO 
1903,  INCLUSIVE 


{From  Report  of  the  Commissioner  o 

F  Navigation) 

Sailing  Vessels 

Steam  Vessels 

Year 

Num- 

Gross 

Num- 

Gross 

ber 

Tonnage 

ber 

Tonnage 

1868 

910 

874 

142,742 
149,029 

236 
279 

63,940 

1869 

65,066 

1870 

816 

146,340 

290 

70,621 

1871 

756 

97,176 

302 

87,842 

1872 :... 

645 

76,291 

292 

62,210 

1873 

804 

144,62© 

402 

88,010 

1874 

961 

216,316 

404 

101,930 

1875 

798 

206,884 

323 

62.460 

1876 

698 

118,672 

338 

69,252 

1877 

581 

106,331 

265 

47,514 

1878 

532 

106,066 

334 

81,860 

1879 

468 

66,867 

335 

86,361 

1880 

460 
493 

59,057 
81,209 

348 
444 

78  053 

1881 

118,070 

1882 

666 
721 

118,798 
137.046 

502 
439 

121  843 

1883 

107,229 

1884 

706 

120,621 

410 

91,328 

1885 

533 

65,362 

338 

84.332 

1886 

405 

41,237 

240 

44,467 

1887 

447 

34,633 

299 

100,074 

1888  .... 

423 
489 
505 
733 

48,590 

50,570 

102.873 

144,290 

430 
440 
410 

488 

142  006 

1889 

159  318 

1890 

159  045 

1891 

185,037 

1892 

846 
493 

83.217 
49,348 

438 
380 

92  531 

1893 

134,308 

1894 

477 
397 

37,827 
34,900 

293 
248 

83  720 

1895 

69,754 

1896 

369 

65,236 

286 

138,028 

1897 

338 

64,308 

288 

106,153 

1898 

359 

34,416 

394 

105,838 

1899 

420 

98,073 

439 

151,058 

1900 

504 

116,460 

422 

202,528 

1901 

526 

126,165 

506 

273,591 

1902 

581 

97,698 

579 

308,178 

1903 

470 

89,979 

551 

271,781 

NoTB. — Cfnal  boats  and  barges  are  not  included  In  this  table. 


NAUTICAL  MEMORANDA 


509 


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311 


In  the  preceding  tables,  giving  an  estimate  of  the  sea 
strength  of  the  principal  naval  powers  in  July,  1905,  the 
figures  for  Russia  and  Japan  are  revised  to  include  changes 
brought  about  by  the  gains  and  losses  during  the  war.  In 
the  classification  of  the  ships  the  term  protected  cruiser  has 
been  omitted,  because  all  cruisers,  except  the  smallest  and 
oldest,  now  have  protective  decks.  Scouts  are  considered 
as  cruisers  in  which  battery  and  protection  have  been 
sacrificed  to  secure  extreme  speed.  It  should  be  further 
noted  that  in  this  comparison  the  following  vessels  are  not 
included:  Those  over  20  yr.  old,  unless  they  have  been 
reconstructed  and  rearmed;  those  not  actually  completed; 
gunboats  and  other  vessels  of  less  than  1,000  T.;  and  lastly, 
torpedo  craft  of  less  than  50  T.  displacement. 

NUMBER  AND  TONNAGE  OF  THE  MERCHANT  MARINE 
OWNED  BY  THE  PRINCIPAL  MARITIME  NATIONS 

{From  Report  by  the  Department  of  Commerce  and  Labor  1905) 


Country 

Sailing  Vessels 
50  T.  and  More 

Steamers 
100  T.  and  More 

Num- 
ber 

Tonnage 

Num- 
ber 

Tonnage 

Great  Britain 

United  States 

6.839 

3,751 

1,740 

3,006 

1,449. 

914 

1,554 

1,515 

867 

1,521 

911 

797 

704 

576 

374 

278 

111 

163 

120 

2,196,443 

1,454.152 

767.981 

545,087 

535,703 

528,267 

517,964 

278,445 

174,824 

174,624 

173,636 

126,135 

104,722 

94,294 

76.375 

60.736 

51,886 

40.540  ' 

29.118  j 

5,929 

846 

844 

533 

556 

1,193 

351 

594 

99 

373 

180 

341 

304 

403 

186 

26 

38 

93 

224 

13.966,972 

1,610.466 

925  683 

Russia .... 

593  742 

1,139  575 

Germany. . 

2  767  463 

Italv 

714  .SS7 

Sweden 

473  051 

Turkey 

98  066 

Japan 

556  036 

Greece .  . 

321  330 

477  087 

Holland 

608  153 

712  804 

Brazil 

Portugal. . .    . 

123.597 
45  633 

ChiH 

62  742 

Argentina 

Austria 

73,128 
540,354 

312 


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TO  PRODUCE  BREATHIXG  315 

The  new  White  Star  liner  "Baltic,"  whose  dimensions  are 
given  in  the  preceding  table,  is  probably  better  equipped 
electrically  than  any  other  vessel,  either  afloat  or  building.  In 
addition  to  the  usual  electrical  appliances  to  be  found  on 
board  present-day  ocean  liners,  the  "Baltic"  is  equipped  with 
an  electrical  device  for  preventing  collisions  with  other 
vessels.  The  moment  another  ship  enters  the  magnetic 
field  of  the  "Baltic,"  the  needle  of  the  indicating  instrument 
points  in  the  direction  of  the  vessel  approaching,  or  being 
overtaken,  and  the  officer  in  charge  of  the  deck  is  thus  in 
a  position  to  take  the  steps  necessary  to  avoid  a  collision. 
Even  the  rhythmic  beats  of  an  unseen  steamer's  screws  are 
registered  by  means  of  this  delicate  apparatus.  Another 
safeguard  is  an  electric  contrivance  to  show  on  the  bridge 
if  the  ship's  lights  are  burning  properly.  An  electric  log 
for  ascertaining  the  speed  of  the  ship  is  another  acquisition, 
and  an  electric  lead  for  sounding  is  also  on  the  list.  There 
is,  further,  an  electric  device  for  registering  all  signals, 
including  steam  sirens.  The  "Baltic"  is  equipped  with  elec- 
tric refrigerating  as  well  as  electric  cooking  apparatus. — 
Scientific  American. 

TO  RESTORE  APPARENTLY  DROWNED 
PERSONS 

TREATMENT    WHEN    SEVERAL    ASSISTANTS    ARE    ON 
HAND 

As  soon  as  the  patient  is  taken  from  the  water,  expose 
the  face  to  the  air,  toward  the  wind  if  there  be  any,  and 
wipe  dry  the  mouth  and  nostrils;  rip  the  clothing  so  as  to 
expose  the  chest  and  waist,  and  give  two  or  three  quick, 
smarting  slaps  on  the  chest  with  the  open  hand.  If  the 
patient  does  not  revive,  proceed  immediately  to  expel  water 
from  the  stomach  and  chest,  as  follows:  Separate  the  jaws 
and  keep  them  apart  by  placing  between  the  teeth  a  cork  or 
small  bit  of  wood;  turn  the  patient  on  his  face,  a  large  bundle 
of  tightly  rolled  clothing  being  placed  beneath  the  stomach 
(see  Fig.  1) ;  press  heavily  on  the  back  over  the  stomach  for 
^  min.,  or  as  long  as  fluids  flow  freely  from  the  mouth. 


316 


TO  PRODUCE  BREATHING 


To  Produce  Breathing. — Clear  the  mouth  and  throat  of 
mucus  by  introducing  into  the  throat  the  comer  of  a  hand- 
kerchief  wrapped   closely  around   the   forefinger;   turn  the 


Fig.  1 

patient  on  the  back,  the  roll  of  clothing  being  so  placed  as 
to  raise  the  pit  of  the  stomach  above  the  level  of  the  rest  of 


Fig.  2 

the  body  (see  Fig.  2).  Let  an  assistant,  with  a  handkerchief 
or  piece  of  dry  cloth,  draw  the  tip  of  the  tongue  out  of  one 
comer  of  the  mouth  (which  prevents  the  tongue  from  falling 


TO  PRODUCE  BREATHING 


317 


back  and  choking  the  entrance  to  the  windpipe),  and  keep 
it  projecting  a  little  beyond  the  lips.  Let  another  assistant 
grasp  the  arms  just  below  the  elbows  and  draw  them  steadily 
upwards  by  the  side  of  the  patient's  head,  and  to  the  ground, 
the  hands  nearly  meeting  (which  enlarges  the  capacity  of 
the  chest  and  induces  inspiration).  While  this  is  being 
done,  let  a  third  assistant  take  a  position  astride  the  patient's 
hips,  with  his  elbows  resting  on  his  own  knees,  his  hands 
extended  ready  for  action.  Next,  let  the  assistant  stand- 
ing at  the  head  turn  down  the  patient's  arms  to  the  side  of 
the   body    (see   Fig.    3),   the   assistant   holding   the   tongue 


7f  "^v'^^''t^ 


Fig.  3 

changing  hands,  if  necessary,  to  let  the  arm  pass.  Just 
before  the  patient's  hands  reach  the  ground,  the  man  astride 
the  body  will  grasp  the  body  with  his  hands,  the  balls  of 
the  thumbs  resting  on  either  side  of  the  pit  of  the  stomach, 
the  fingers  falling  into  grooves  between  the  short  ribs. 
Now,  using  his  knees  as  a  pivot,  he  will  at  the  moment 
the  patient's  hands  touch  the  ground  throw  (not  too  sud- 
denly) all  his  weight  forwards  on  his  hands,  and  at  the 
same  time  squeeze  the  waist  between  them,  as  if  he  wished 
to  force  something  in  the  chest  upwards  out  of  the  mouth; 
he  will  increase  the  pressure  while  he  slowly  counts  one, 
two,  three,  four  (about  5  sec),  then  suddenly  let  go  with 


318  TO  PRODUCE  BREATHING 

a  final  push,  which  will  spring  him  back  to  his  first  position. 
This  completes  expiration. 

At  the  instant  the  pressure  is  taken  from  the  waist  the 
man  at  the  patient's  head  will  again  steadily  draw  the  arms 
upwards  to  the  sides  of  the  patient's  head,  as  before  (the 
assistant  holding  the  tongue  again  changing  hands  to  let 
the  arm  pass,  if  necessary),  holding  them  there  while  he 
slowly  counts  one,  two,  three,  four  (about  5  sec). 

Repeat  these  movements,  deliberately  and  perseveringly, 
12  to  15  times  in  every  minute — thus  imitating  the  natural 
motions  of  breathing. 

If  natural  breathing  is  not  restored  after  a  trial  of  the 
bellows  movement  for  the  space  of  about  4  min.,  then 
turn  the  patient  a  second  time  on  the  stomach,  rolling  the 
body  in  the  opposite  direction  from  that  in  which  it  was 
first  turned,  for  the  purpose  of  freeing  the  air  passage 
from  any  remaining  water.  Continue  the  artificial  respi- 
ration from  1  to  4  hr.,  or  until  the  patient  breathes,  accord- 
ing to  the  preceding  instructions;  and  for  a  time,  after  the 
appearance  of  returning  life,  carefully  aid  the  short  gasps 
until  deepened  into  full  breaths.  Continue  the  drying  and 
rubbing,  which  should  have  been  unceasingly  practiced 
from  the  beginning  by  assistants,  taking  care  not  to  interfere 
with  the  means  used  to  produce  breathing.  Thus  the  limbs 
of  the  patient  should  be  rubbed,  always  in  an  upward 
direction  toward  the  body  with  firm,  grasping  pressure 
and  energy,  using  the  bare  hands,  dry  flannels,  or  handker- 
chiefs, and  continuing  the  friction  under  the  blankets  or 
over  the  dry  clothing.  The  warmth  of  the  body  can  also  be 
promoted  by  the  application  of  hot  flannels  to  the  stomach 
and  armpits  and  bottles  or  bladders  of  hot  water,  heated 
bricks,  etc.,  to  the  limbs  and  soles  of  the  feet. 

After  Treatment. — When  breathing  has  been  established, 
let  the  patient  be  stripped  of  all  wet  clothing,  wrapped  in 
blankets  only,  put  to  bed  comfortably  warm,  but  with  free 
circulation  of  fresh  air.  and  left  to  perfect  rest.  Give 
whisky,  or  brandy,  and  hot  water  in  doses  of  a  teaspoonful, 
or  a  tablespoonful,  according  to  the  weight  of  the  patient, 
or  any  other  stimulant  at  hand,  every  10  or  15  min.  for  the 


TO  PRODUCE  BREATHING 


319 


first  hour,  and  as  often  thereafter  as  may  seem  expedient. 
After  reaction  is  fully  established,  there  is  great  danger  of 
congestion  of  the  lungs,  and  if  perfect  rest  is  not  maintained 
for  at  least  48  hr.,  it  sometimes  occurs  that  the  patient  is 
seized  with  great  difficulty  of  breathing,  and  death  is  liable 
to  follow  unless  immediate  relief  is  afforded.  In  such  cases, 
apply  a  large  mustard  plaster  over  the  breast.  If  the  patient 
gasps  for  breath  before  the  mustard  takes  effect,  assist  the 
breathing  by  carefully  repeating  the  artificial  respiration. 

The  foregoing  treatment  should  be  persevered  in  for  some 
hours,  as  it  is  an  erroneous  opinion  that  persons  are  irrecover- 
able because  life  does  not  soon  make  its  appearance,  persons 
having  been  restored  after  persevering  for  many  hours. 

MODIFICATION  OF  TREATMENT  IN  CASE  NO  ASSIST- 
ANT IS  AT  HAND 
To  Produce  Respiration. — If  no  assistant  is  at  hand  and 
one  person  must  work  alone,  place  the  patient  on  his  back 
with  the  shoulders  slightly  raised  on  a  folded  article  of 
clothing;  draw  forward  the  tongue  and  keep  it  projecting 
just  beyond  the  lips;  if  the  lower  jaw  be  lifted,  the  teeth 


Fig.  1 


may  be  made  to  hold  the  tongue  in  place;  it  may  be  neces- 
sary to  retain  the  tongue  by  passing  a  handkerchief  under 
the  chin  and  tying  it  over  the  head.  Grasp  the  arms  just 
below  the  elbows  and  steadily  draw  them  upwards  by  the 
sides  of  the  patient's  head  to  the  ground,  the  hands  nearly 


320 


U.  S.  NATURALIZATIOX  LAWS 


meeting  as  shown  in  Fig.  1.  Next,  lower  the  arms  to  the 
sides  and  press  firmly  downwards  and  inwards  on  the  sides 
and  front  of  the  chest  over  the  lower  ribs,  drawing  toward 
the  patient's  head,  as  shown  in  Fig.  2.  Repeat  these  move- 
ments 12  to  15  times  every  minute,  etc. 

Remarks. — In    any    operation    for    restoring    to    life    an 
apparently  drowned  person,  remember  the  following: 


Fig.  2 

Prevent  unnecessary  crowding  of  persons  round  the  body, 
especially  if  in  an  apartment. 

Avoid  rough  usage,  and  do  not  allow  the  body  to  remain 
on  the  back  unless  the  tongue  is  secured. 

Under  no  circumstances  hold  the  body  up  by  the  feet. 

On  no  account  place  the  body  in  a  warm  bath,  unless 
tinder  medical  direction,  and  even  then  it  should  only  be 
employed  as  a  momentary  excitant. 


U.  S.  NATURALIZATION  LAWS 

The  conditions  and  manner  of  admission  of  an  alien  to 
the  citizenship  of  the  United  States  are  prescribed  by  Sec- 
tion 2,  165-74  of  the  Revised  Statutes  of  the  United  States. 

Declaration  of  Intentions. — The  alien  must  declare  on 
oath  before  a  circuit  or  district  court  of  the  United  States, 
or  a  district  or  supreme  court  of  the  territories,  or  a  court  of 
record  of  any  of  the  states  having  common-law  jurisdiction 


U.  S.  NATURALIZATION  LAWS  321 

and  a  seal  and  clerk,  2  yr.  at  least  prior  to  his  admission, 
that  it  is,  bona  fide,  his  intention  to  become  a  citizen  of  the 
United  States,  and  to  renounce  forever  all  allegiance  and 
fidelity  to  any  foreign  prince  or  state,  and  particularly  to  the 
one  of  which  he  may  be  at  the  time  a  citizen  or  subject. 

Oath  on  Application  for  Admission. — He  must,  at  the  time 
of  his  application  to  be  admitted,  declare  on  oath,  before  some 
one  of  the  courts  above  specified,  "that  he  will  support  the 
constitution  of  the  United  States,  and  that  he  absolutely 
and  entirely  renounces  and  abjures  all  allegiance  and  fidelity 
to  every  foreign  prince,  potentate,  state,  or  sovereignty  of 
which  he  was  before  a  citizen  or  subject,"  which  proceedings 
must  be  recorded  by  the  clerk  of  the  court. 

Conditions  for  Citizenship. — If  it  shall  appear  to  the  satis- 
faction of  the  court  to  which  the  alien  has  applied  that  he 
has  made  a  declaration  of  intention  to  become  a  citizen  2  yr. 
before  applying  for  final  papers,  and  has  resided  continuously 
within  the  United  States  for  at  least  5  yr.,  and  within  the 
state  or  territory  where  such  court  is  at  the  time  held  1  yr. 
at  least;  and  that  during  the  time  "he  has  behaved  as  a  man 
of  good  moral  character,  attached  to  the  principles  of  the 
constitution  of  the  United  States,  and  well  disposed  to  the 
good  order  and  happiness  of  the  same,"  he  will  be  admitted 
to  citizenship. 

Seamen. — Any  seaman,  who  is  a  foreigner,  who  declares 
his  intention  of  becoming  a  citizen  of  the  United  States,  in 
any  competent  court,  and  has  served  3  yr.  on  board  a 
merchant  vessel  of  the  United  States  subsequent  to  the  date 
of  his  declaration,  may,  on  his  application  to  any  competent 
court,  and  on  the  production  of  a  certificate  of  discharge 
and  good  conduct  during  that  time,  together  with  the  cer- 
tificate of  his  declaration  of  intention  to  become  a  citizen, 
be  admitted  to  citizenship  in  the  United  States. 

Persons  Discharged  From  United  States  Navy  or  Marine 
Corps. — Any  alien  of  the  age  of  21  yr.  and  upwards,  who  has 
enlisted  or  may  enlist  in  the  United  States  Navy  or  Marine 
Corps,  and  has  served  or  may  hereafter  serve  5  consecutive 
years  in  the  United  States  Navy,  or  one  enlistment  in  the 
Marine  Corps,  and  has  been,  or  may  hereafter  be,  honorably 


322  U.  5.  XATURALIZATION  LAWS 

discharged,  may  be  admitted  to  citizenship  without  a  pre- 
vious declaration  of  his  intention  to  become  a  citizen. 

Minors. — Any  aHen  under  the  age  of  21  yr.  who  has 
resided  in  the  United  States  during  the  3  yr.  next  prece- 
ding his  arriving  at  that  age,  and  who  has  continued  to 
reside  therein  to  the  time  of  his  application  to  be  admitted 
a  citizen  thereof,  may,  after  he  arrives  at  the  age  of  21  yr., 
and  after  he  has  resided  5  yr.  within  the  United  States, 
including  the  3  yr.  of  his  minority,  be  admitted  a  citizen, 
but  he  must  make  a  declaration  on  oath  and  prove  to  the 
satisfaction  of  the  court  that  for  the  2  yr.  next  preceding,  it 
has  been  his  bona  fide  intention  to  become  a  citizen. 

Children  of  Naturalized  Citizens. — The  children  of  persons 
who  have  been  duly  naturalized,  being  under  the  age  of  21  yr. 
at  the  time  of  the  naturalization  of  their  parents,  shall,  if 
dwelling  in  the  United  States,  be  considered  as  citizens 
thereof. 

Chinese. — The  naturalization  of  Chinamen  is  expressly 
prohibited  by  Section  14,  Chapter  126,  Laws  of  1882. 

Protection  Abroad  to  Naturalized  Citizens. — Section  2,000 
of  the  Revised  Statutes  of  the  United  States  declares  that 
"all  naturalized  citizens  of  the  United  States  while  in  foreign 
countries  are  entitled  to  and  shall  receive  from  this  govern- 
ment the  same  protection  of  persons  and  property  which  is 
accorded  to  native-born  citizens." 

Right  of  Suffrage. — The  right  to  vote  comes  from  the  state, 
and  is  a  state  gift.  Naturalization  is  a  federal  right,  and  is 
a  gift  of  the  Union,  not  of  any  one  state.  In  nearly  one-half 
of  the  Union,  aliens  (who  have  declared  intentions)  vote  and 
have  the  right  to  vote  equally  with  naturalized  or  native- 
born  citizens.  In  the  remaining  states,  only  actual  citizens 
may  vote.  The  federal  naturalization  laws  apply  to  the 
whole  Union  alike,  and  provide  that  no  alien  may  be  natu- 
ralized until  after  5  yr.  residence.  Even  after  5  yr.  resi- 
dence and  due  naturalization,  he  is  not  entitled  to  vote 
unless  the  laws  of  the  state  confer  the  privilege  upon  him; 
but  in  several  states  he  may  vote  6  mo.  after  landing,  if 
he  has  declared  his  intention,  under  United  States  law,  to 
become  a  citizen. 


CUSTOM-HOUSE  FEES  323 

CUSTOM-HOUSE  FEES 

The  following  is  a  partial  list  of  the  custom-house  fees  and 
other  charges  required  by  law  to  be  paid  by  vessels  at  the 
several  custom  houses  in  the  United  States: 
Entry  of  vessel  of  100  T.  or  more  from  foreign  port ...  .$2 .50 
Clearance  of  vessel  of  100  T.  or  more  to  foreign  port. . .   2  .50 

Entry  of  vessel  under  100  T.  from  foreign  port 1 .50 

Clearance  of  vessel  under  100  T.  to  foreign  port 1 .  50 

Post-entry 2 .  00 

Permit  to  land  or  deliver  goods 20 

Bond  taken  officially 40 

Debenture,  or  other  official  certificate 20 

Bill  of  health 20 

For  recording  bill  of  sale,  mortgage,  hypothecation  or 

conveyance  of  vessel,  under  Act  of  July  29,  1850.  .  .      .50 
For  recording  a  certificate  for  discharging  and  cancel- 
ling any  such  conveyance 50 

For  furnishing  a  certificate  setting  forth  the  names  of 
the  owners  of  any  registered  or  enrolled  vessel,  the 
parts  or  proportions  owned  by  each,  and  also  the 
material  facts  of  any  existing  bill  of  sale,  mortgage, 
hypothecation  or  other  encumbrance,  the  date, 
amount  of  such  encumbrance,  and  from  and  to  whom 

made 1.00 

For  furnishing  copies  of  such  records,  for  each  bill  of 

sale,  mortgage,  or  other  conveyance 50 

Certificate  of  registry,  including  bond  and  oath 2.25 

Indorsement   on   certificate   of   registry   of   change   of 

master 1 .  00 

For  every  bond  under  the  Registry  Act 25 

Certificate  of  enrolment 50 

Indorsement  on  certificate  of  enrolment,  of  change  of 

master,  etc 20 

License,  and  granting  the  same,  including  bond  and 

oath,  if  not  over  100  T 70 

License,  and  granting  the  same,  over  100  T 1 .20 

License,  vessel  not  over  20  T.,  including  bond  and  oath      .45 
Indorsement  on  a  license  of  change  of  master,  etc 20 


324  CUSTOM-HOUSE  FEES 

Certifying  manifest,  and  granting  permit  for  licensev^. 

vessels  to  go  from  district  to  district $    .10 

Receiving  certified  manifest,  and  granting  permit  on 
arrival  of  such  vessel 10 

Certifying  manifest,  and  granting  permission  to  regis- 
tered vessels  to  go  from  district  to  district 1 .  50 

Receiving  certified  manifest,  and  granting  permit  on 
arrival  of  such  registered  vessel 1 .  00 

Granting  permit  to  a  vessel,  not  belonging  to  a  citizen 
of  the  United  States,  to  go  from  district  to  district, 
and  receiving  manifest 2  .  00 

Receiving  manifest  and  granting  permit  to  unload,  to  a 
vessel  not  belonging  to  an  American  citizen,  on  arrival 
at  one  district  from  another 2 .  00 

Services  other  than  admeasurement  to  be  performed  by 
the  Surveyor  in  vessels  of  100  T.  or  more,  having 
on  board  merchandise  subject  to  duty 3 .  00 

For  like  service  in  vessels  under  100  T.,  having  similar 
merchandise 1 .  50 

For  like  services  in  all  vessels  not  having  merchandise 

subject  to  duty 67 

Protection  to  American  seamen 25 

Crew  list 25 

General  permit  to  land  passengers'  baggage 20 


NIENIOI^^NDA 


NIKMORANDA 


NIENIOR^NDA 


NIENIORANDA 


MiENlORANDA 


NIENIORANDA 


Promotion 
y vancement  in  Salary 

and 

'  Business  Success  ^ 


Secured 
Through  the 

Marine  Engineers' 
and  Ocean,  Lake,  and 
Coastwise  Navigation 

COURSES  OF  INSTRUCTION 

OF   THE 

International 
Correspondence  Sciiools 

International  Textbook 
Company,    Proprietors 

SCRANTON,  PA.,  U.S.A. 


SEE  FOLLOWING  PAGES 


Passed  Many  Exam- 
inations 

I  wish  to  say  that  your  Schools  are  all  O.  K. 
They  have  been  instrumental  in  my  being 
able  to  pass  the  following  examinations: 
Assistant  Engineer,  U.  S.  N.,  Spanish  Ameri- 
can War;  Warrant  Machinist,  U.  S.  N.,  Regular 
Service;  Chief  Engineer,  U.  S.  Coast  Survey; 
Chief  Engineer,  U.  S.  Quartermaster's  Depart- 
ment, U.  S.  Army;  and  I  have  just  passed  as 
Local  Inspector  of  Boilers,  of  Ocean  Steamers 
of  10,000  tons.  I  not  only  passed  all  of  these 
examinations,  but  have  been  appointed  to  all 
but  the  Local  Inspector  of  Boilers,  and  I  hope 
to  be  in  it  before  the  summer  is  over.  I  now 
fill  the  position  of  Chief  Engineer  on  board 
one  of  the  U.  S.  Quartermaster's  Boats,  U.  S. 
Army.  I  would  have  been  unable  to  pass  all 
of  these  examinations,  all  of  them  being  very 
hard,  if  I  had  not  studied  in  your  Schools. 

Any  time  I  can  do  anything  for  you  let  me 
know,  as  your  School  is  a  Godsend  to  practical 
men,  but  I  am  sorry  to  say  that  a  great  many 
do  not  see  it.  It  was  one  of  your  circulars 
that  set  me  thinking.  It  was  as  follows: 
"A  man  cannot  stand  still;  he  either  goes 
ahead  or  lags  behind." 

D.  C.  Young, 
625  Apple  ton  St.,  Baltimore,  Md. 


PROMOTED  TO  ENSIGN 

W.  D.  Greetham,  Ensign,  U.  S.  N.,  Washington,  D.  C. 
says  he  thinks  very  highly  of  the  I.  C.  S.  and  is  confident 
he  owes  his  recent  advancement  to  the  rank  of  ensign  to 
the  information  gained  by  studying  the  I.  C.  S.  Navigation 
Course. 

FIREMAN  BECOMES  WARRANT  MACHINIST 

T.  G.  Sprengel.  Warrant  Machinist,  U.  S.  N.,  U.  S.  S. 
"Massachusetts,"  could  not  ship  in  the  United  States  Navy 
as  a  machinist  because  he  didn't  have  sufficient  knowledge. 
He  went  as  a  fireman,  second  class.  By  studying  the 
I.  C.  S.  Course  he  has  now  reached  the  position  of  warrant 
machinist  in  the  Navy.  He  says  he  would  not  take  one 
hundred  times  the  cost  of  the  Course  for  the  benefit  received 
from  it. 

COAL  PASSER  BECOMES  ELECTRICIAN 

A.  M.  H.wiRiCK,  Electrician,  U,  S.  N.,  U.  S.  S.  "Prince- 
ton," enrolled  in  the  I.  C.  S.  while  a  coal  passer  in  a  boiler 
room.  At  the  present  time  he  is  electrician  on  board  the 
U.  S.  S.  "  Princeton,"  and  his  salary  has  been  increased  about 
200  per  cent. 

OBTAINED  UNLIMITED  LICENSE 

W.  G.  MiCHALSKi,  807  South  Broadway,  Baltim.ore,  Md., 
passed  the  examination  for  chief  mate  on  ocean-going 
steamers  and  has  been  given  an  unlimited  license  for  that 
position.  He  also  has  been  promoted  from  second  officer 
to  the  position  of  chief  officer.  Mr.  Michalski  thanks  the 
I.  C.  S.  for  his  success. 

PASSED  EXAMINATIONS  EASILY 

William  J.  Ryan*,  53  North  Main  St.,  W^oonsocket,  R.  I., 
by  studying  the  Ocean  Navigation  Course,  has  successfully 
passed  examination  for  the  position  of  second  mate  on 
ocean  steam  vessels. 


EASILY  UNDERSTOOD  AND  MOST  INTERESTING 

Charles  Liess.m.»n,  U.  S.  S.  "  Marblehead,"  in  a  letter  to 
the  Schools  says  the  Course  has  proved  to  be  most  interesting 
and  simple;  that  he  cotild  not  help  mastering  the  subjects. 

IS  PILOT  ON  GREAT  LAKES  NOW 

Henry  Ericksen,  670  Seventh  St.,  Milwaukee,  Wis.,  passed 
the  United  States  examination  for  pilot  on  the  Great  Lakes, 
by  means  of  his  studies  with  the  I.  C.  S.  His  salary  has 
been  increased  130  per  cent. 

3 


The  Course  a  Great 
Benefit 

I  found  the  International  Correspondence 
Schools'  Ocean  Navigation  Course  of  the 
greatest  benefit  to  me.  And  the  Reference 
Library  Volumes  not  only  have  proved  most 
useful  when  preparing  for  examination  and 
as  books  of  reference  for  actually  working 
navigation  at  sea,  but  they  have  been 
admired  by  every  officer  in  the  service  who 
has  seen  them. 

Henry  B.  Soulek,  Lieutenant,  U.  S.  N., 
Bureau  of  Navigation, 

Washington,  D.  C. 


PASSED  AN  EXAMINATION 

William  Santimo,  Brechin,  Ont.,  by  studying  the  Lake 
Navigation  Course,  has  been  able  to  pass  an  examination  for 
a  mate's  certificate. 

PRAISE  FROM  GOVERNMENT  OFFICERS 

WiLHELM  Weidlick,  Puget  Sound  Harbor  16,  Seattle, 
Wash.,  prepared  for  a  mate's  certificate  by  studying  the 
1.  C.  S.  Course  in  Ocean  Navigation.  He  passed  with  flying 
colors.  Captain  Pratt,  of  the  United  States  Coast  and 
Geodetic  Survey,  and  many  other  prominent  ship  masters, 
declared,  in  this  connection,  that  the  Course  is  the  most 
complete  work  of  its  kind  they  ever  have  seen. 

COXSWAIN  BECOMES  THIRD  OFFICER 

Andrew  E.  Knudson,  New  York,  passed  the  Board  of 
Inspectors'  examination  and  is  now  serving  as  third  officer 
on  board  of  the  "  El  Vail,  "  of  New  York.  When  he  enrolled 
in  the  I.  C.  S.  he  was  a  coxswain  in  the  Navj'. 

BECOMES  FIRST-CLASS  PILOT 

R.  R.  WiLMOT,  948  Jefferson  Ave.,  Brooklyn,  N.  Y..  was 
an  unlicensed  man,  acting  as  third  mate  on  a  steamship 
when  he  began  studying  in  the  I.  C.  S.  He  has  passed  the 
examination  for  master  of  ocean  steam  vessels  and  for  fi.rst 
chief  pilot.  He  is  now  second  officer  of  the  S.  S.  "El  Mar" 
and  a  member  of  the  American  Masters,  Mates,  and  Pilots' 
Association.  He  says  there  never  has  arisen  during  his 
service  at  sea  a  problem  in  nautical  science  that  he  has  not 
been  able  to  solve  by  means  of  the  knowledge  gained  from 
his  Course. 

FROM  DECKHAND  TO  BOATSWAIN 

Bertolf  Mathiesen,  815  Witherspoon  Bldg.,  Phila- 
delphia, Pa.,  took  up  the  Ocean  Navigation  Course  and  in 
a  few  months  was  promoted  to  the  position  of  quarter- 
master on  the  Government  dredge  "Delaware,"  which 
carries  56  men.  In  11  months  from  the  time  of  his  enrol- 
ment he  was  made  boatswain.  He  gives  the  I.  C.  S.  entire 
credit  for  his  quick  promotions. 

SEAMAN  TO  COXSWAIN 
Ferdinand  Johansen,  U.  S.  S.  "Alliance,"  Culelera, 
Porto  Rico,  says  the  I.  C.  S.  Ocean  Navigation  Course  is 
excellent.  He  learned  from  it  the  rules  of  the  road,  safety 
arrangements,  and  information  about  codes  and  steam 
launches.  He  has  advanced  from  ordinary  seam^an  in  the 
United  States  Navy  to  coxswain  of  a  forty-foot  steam 
launch  with  corresponding  increases  in  wages. 


Simple  and  Thorough 

I  take  pleasure  in  saying  that  the  Naviga- 
tion Course  of  the  International  Correspond- 
ence Schools  is  the  most  simple  and  thorough 
method  for  a  student  to  learn  navigation. 
Having  but  a  limited  common-school  educa- 
tion and  having  received  a  Diploma  with  no 
assistance  outside  the  School,  is  a  voucher  of 
the  School's  gviarantee.  You  are  at  perfect 
liberty  to  refer  to  me  at  any  time  that  I  can 
be  of  service  to  you,  and  it  will  give  me  great 
pleasure  to  recommend  the  Schools  whenever 
I  have  the  opportunity. 

With  kind  regards,  I  remain, 

William  Henry  Caoss, 

Bar  Pilot,  Charleston,  S.  C. 


FROM  DECK  HAND  TO  MATE 

Henry  E.  Farrer,  South  Bend,  Wash.,  holds  a  mate's 
license  that  he  was  able  to  win  by  studying  the  Lake  Naviga- 
tion Course.  At  present  he  is  n-.ate  of  a  tug,  earning  875 
a  month  and  board.  When  he  enrolled  he  was  deck  hand 
on  a  steamer,  earning  S45  a  month. 

FROM  SEAMAN  TO  THIRD  OFFICER 

A.  Frederiksex,  1310  Laguna  St.,  San  Francisco,  Cal., 
says  he  does  not  know  of  a  school  in  the  United  States, 
outside  of  the  Naval  Academy,  so  good  as  the  I.  C.  S. 
Ocean  Navigation  School.  He  says  every  subject  per- 
taining to  ordinary  practical  navigation  is  fully  treated  and 
that  the  Course  gives  an  education  far  beyond  any  required 
to  pass  the  examinations  for  unlimited  license  as  master  or 
mate  of  steam  or  sailing  vessels.  When  he  enrolled  in  the 
I.  C.  S.  he  was  a  seaman  in  the  United  States  Navy.  At 
present  he  is  third  officer  of  the  steamship  "City  of  Tara." 
His  salary  has  been  increased  250  per  cent. 

COAL  PASSER  TO  ENGINEER 

W.  H.  Demeritt,  U.  S.  S.  "Mangrove."  Key  West,  Fla., 
has  advanced  from  the  position  of  coal  passer,  in  the  light- 
house service,  to  second  in  charge  of  the  engineering  depart- 
ment of  one  of  the  largest  steamers  in  the  United  States 
light-house  service — the  U.  S.  S.  "Mangrove."  It  didn't 
take  Mr.  Demeritt  long  to  master  the  Course;  and  at  the 
examination  he  made  the  highest  percentage  on  record  in 
his  district. 

FROM  $18  A  MONTH  TO  $1,000  A  YEAR 

Stanley  S.  Stevens,  Delaware  City,  Del.,  enrolled  in  the 
I.  C.  S.  Marine  Engineers'  Course  while  earning  about  S18 
a  month.  What  he  learned  from,  the  Course  enabled  him 
to  pass  the  Government  examination  for  marine  engineers' 
license.  He  is  now  earning  SI, 000  a  year  and  says  he  owes 
his  position  entirely  to  I.  C.  S.  instruction. 

WATCHMAN  PASSES  PILOTS'  EXAMINATION 

R.  C.  LuDWiG,  162  Broadway,  Benton  Harbor,  Mich., 
enrolled  for  the  Lake  Navigation  Course  while  holding  a 
position  as  watchman  on  a  lake  steamer.  With  the  knowl- 
edge gained  from  his  Course  he  passed  the  examination  for 
first-class  pilot,  of  all  tonnage  for  Lake  Michigan,  Green 
Bay,  and  the  Straits  of  Mackinaw.  Last  season  he  held  a 
position  as  second  officer  on  a  steamer  and  received  commen- 
dation from  his  superior  officers.  Mr.  Ludwig  is  going  to 
continue  his  studies  with  us  until  he  secures  a  first-class 
license  for  all  the  Great  Lakes  and  connecting  waters.  His 
salary  has  increased  70  per  cent. 


Commendation  From  a 
Commander 

I  received  the  Volumes  of  your  Course  in 
Navigation  several  weeks  ago  and  have 
examined  them  with  much  interest.  They 
seem  to  me  admirably  adapted  both  in  plan 
and  in  execution  to  the  purpose  for  which 
they  are  designed,  and  I  am  sure  that  the 
Course  of  Instruction  which  they  represent 
cannot  fail  to  be  of  great  value  to  all  who  may 
take  it  under  your  guidance. 

The  two  features  of  the  work  which  have 
impressed  me  most  forcibly  are:  first,  the 
happy  balancing  of  theory  and  practice;  and 
second,  the  originality  and  helpfulness  of  the 
illustrations. 

Austin  M.  Knight, 

Commander,  U.  S.  Navy 


PASSED  EXAMINATION  FOR  FIRST-CLASS  PILOT 

Thomas  Wilmot,  U.  S.  Steamer  "Morrill,"  Milwaukee, 
Wis.,  has  been  able  to  stand  a  stiflf  examination  for  the 
position  of  first-class  pilot,  on  the  Great  Lakes.  He  pre- 
pared for  this  by  studying  the  L  C.  S.  Lake  Navigation 
Course. 

SALARY  INCREASED  140  PER  CENT 

JOHAN  WiLLADSEN,  Sun  Oil  Co.,  Marcus  Hook,  Pa.,  by 
studying  the  Marine  Engineers'  Course  has  advanced  from 
the  position  of  fireman  to  second  engineer,  on  board  the 
steamship  "Paraguay."  From  the  Course  Mr.  Willadsen 
learned  all  about  marine  machinery  and  boilers  and  secured 
sufficient  technical  knowledge  to  obtain  a  marine  engineer's 
license.  His  salary  has  been  increased  140  per  cent,  since 
he  started  studying  the  Course. 

FIREMAN  BECOMES  ENGINEER 

J.  K.  MuNSON,  Shelton,  Wash.,  a  fireman  when  he  enrolled 
in  the  Marine  Engineers'  Course,  is  now  engineer  of  the  tug 
"Victor"  and  his  salary  has  been  increased  over  200  per 
cent.  He  says  he  will  be  glad  to  hear  from  anybody  that 
wants  to  write  to  him  regarding  the  I.  C.  S. 

TUG-BOAT  FIREMAN  BECOMES  MARINE  ENGINEER 

Joseph  H.  Pratt,  1349  Fifth  Ave.,  Watervliet,  N.  Y., 
was  working  as  a  tug-boat  fireman  when  he  began  his  Course 
in  the  L  C.  S.  He  advanced  to  the  position  of  assistant 
engineer  and  then  to  that  of  marine  engineer.  His  salary 
has  doubled  as  a  result  of  studying  the  Course. 

SALARY  DOUBLED 

Charles  Fredrickson,  Fairfield,  Conn.,  by  means  of  the 
Marine  Engineers'  Course,  has  advanced  from  the  position 
of  fireman  to  that  of  second  engineer  on  an  ocean-going  tug 
owned  by  the  Lehigh  Valley  Railroad  Company.  His  salary 
has  been  doubled. 

OILER  BECOMES  ASSISTANT  ENGINEER  AT  $90  A  MONTH 

Emil  Stolsen,  Frankfort,  Mich.,  was  employed  as  an 
oiler  on  one  of  the  Ann  Arbor  Company's  car  ferries  when 
he  started  to  study  the  L  C.  S.  Marine  Engineers'  Course. 
He  is  now  assistant  engineer  for  the  same  company.  His 
salarv  has  been  advanced  from  ?37,.50  to  S90  a  month.  Mr. 
Stolsen  says  that  if  it  was  not  for  the  I.  C.  S.  he  would  have 
been  unable  to  pass  the  examination  required  for  a  marine 
engineer's  license. 


None  Too  Old   to   Learn 


It  gives  me  great  pleasure  to  recommend 
the  I.  C.  S.,  especially  to  marine  engineers. 
I  am  the  owner  of  several  steamers  and  felt 
my  position  very  keenly,  as  I  was  not  able  to 
pass  the  government  examinations  to  secure 
papers  that  Avould  allow  me  to  run  my  own 
boats.  Although  no  longer  a  young  man, 
I  enrolled  for  the  Marine  Engineers'  Course, 
and,  in  a  short  time,  was  able  to  pass  the 
examination  before  the  Government  Inspec- 
tors and  obtain  papers  for  ^OO-ton  steamers 
I  am  convinced  that  if  employes  would  fit 
themselves  for  their  professions  through  the 
Schools  they  would  command  more  respect 
from  their,  employers. 

P.  F.  West.  Bridgeport,  Conn. 


FROM  $90  A  MONTH  TO  $150  A  MONTH 

George  Gale,  310  Twenty-first  St.,  West  New  York, 
N.  Y.,  began  the  Marine  Engineers'  Course  in  the  I.  C.  S. 
while  employed  as  first  assistant  engineer  on  one  of  the 
Southern  Pacific  Company's  steamships.  The  salary  paid 
to  first  assistant  engineers  by  this  company  is  S90  a  month. 
At  present  Mr.  Gale  is  chief  engineer  on  one  of  the  same 
company's  steamships,  running  between  New  York  and 
Galveston.  His  salary  is  ?150  a  month.  He  says  the  knowl- 
edge of  electricity  gained  from  the  Course  was  specially 
valuable  to  him  and  that  the  cost  of  the  Course  is  one  of 
the  best  investments  he  ever  made. 

MACHINIST  STUDIES  THE  COURSE 

W.  A.  Buckley,  U.  S.  S._  "Kentucky,"  care  Postmaster, 
New  York,  was  a  machinist's  apprentice  in  a  marine  engine 
shop  when  he  enrolled  for  the  Marine  Engineers'  Course. 
He  found  the  knowledge  gained  from  the  Course  to  be  of 
much  value  in  connection  with  his  shop  work  and,  later, 
with  his  work  on  board  ship.  He  is  now  chief -machinist's 
mate  in  the  United  States  Navy. 

PASSED  EXAMINATION  FOR  LICENSE 

John  J.  Crowley,  S.  S.  "Larimer,"  Port  Arthur,  Tex., 
had  just  left  an  English  ship,  where  he  was  donkeyman,  and 
taken  a  position  on  an  American  steamer  as  fireman  when 
he  enrolled  in  the  I.  C.  S.  Marine  Engineers'  Course.  By 
studying  he  soon  passed  the  third  assistants'  examination 
for  license  and  immediately  received  an  appointment.  He 
is  going  to  take  the  examination  for  second  assistant,  then 
first  assistant,  and  then  chief. 

FIREMAN  TO  ENGINEER 

S.  Watson,  113  Christiana  St.,  Samia,  Canada,  says  he 
considers  the  I.  C.  S.  instruction  the  best  obtainable  in  the 
lines  taught.  He  enrolled  in  the  Marine  Engineers'  Course 
and  has  advanced  from  the  position  of  fireman  to  that  of 
engineer  of  a  boat. 

RUNS  YACHT  AND  AUTOMOBILE  ENGINES 

Merrill  W.  Keister,  Box  367,  Lake  Geneva,  Wis.,  while 
working  as  a  fireman  on  the  Great  Lakes  tried  to  get  a  license 
as  engineer,  but  failed.  Then  he  enrolled  for  the  I.  C.  S. 
Marine  Engineers'  Course  and  secured  the  much-desired 
license,  together  with  a  position  as  engineer  on  a  private 
yacht,  at  Lake  Geneva,  Wis.  In  the  winter  he  runs  an  auto- 
mobile. His  salary  has  been  advanced  from  S50  a  month  to 
SI  15  a  month. 

11 


Ilnttrb  ^tatrs  Naual  AraJirmg 
Anitapnlta,  Mb. 


International  Correspondence  Schools, 
Scrantott,  Pa. 
Gentlemen:  At  your  request,  I  have  care- 
fully examined  your  textbooks  on  Ocean 
Navigation  and  unhesitatingly  pronounce 
them  an  admirably  arranged  and  compre- 
hensive treatise,  and  one  that  should  prove 
a  valuable  aid  to  any  person  taking  up  the 
study  of  Navigation. 

You  are  to  be  congratulated  on  presenting 
a  subject,   unfortunately  an  intricate  one  to 
many,  in  a  most  clear  and  simple  way. 
W.  C.  P.  MuiR, 
Lieut. -Commander,  U.  S.  N. 


12 


EARNINGS  GREATLY  INCREASED 

W.  J.  Dru.mmond,  Act.  Boatswain,  U.  S.  N,,  U.  S.  S. 
"Siren,"  Navy  Yard,  Norfolk,  Va.,  enrolled  in  the  I.  C.  S. 
while  a  third-class  quartermaster,  earning  S31.36  a  month. 
His  study  with  the  I.  C.  S.  enables  him  to  hold  the  position 
of  boatswain  with  a  salary  of  SI aO  a  month.  Mr.  Drummond 
recently  has  passed  the  examination  for  warrant  rank. 

SEAMAN  BECOMES  MATE 
J.  H.  A.  Johnson,  Boatswain's  Mate,  First  Class,  U.  S.  N., 
Newport,  R.  I.,  is  very  proud  of  his  I.  C.  S.  Diploma,  which 
has  helped  him  to  advance.  When  he  started  to  study  in 
the  I.  C.  S.  he  was  a  seaman  in  the  Navy.  Now  he  is  boat- 
swain's mate,  first  class. 

NOW  SENIOR  STEAM  ENGINEER 

R.  E.  Skeldox,  Toledo,  Ohio,  is  an  example  of  am.bition 
and  I.  C  S.  training  combined  to  make  success.  Mr.  Skeldon 
was  employed  as  engineer  on  a  Government  tug  on  the  Great 
Lakes  when  he  enrolled  in  the  Marine  Engineers'  Course. 
He  applied  himself  to  his  studies  and  now  holds  the  position 
of  senior  steam  engineer  on  the  floating  plant  engaged  in 
United  States  engineering  work  in  the  Cleveland  district. 

NEW  YORK  CLUBMAN  COMMENDS  COURSE 

I  have  put  a  great  deal  of  spare  time,  for  the  last  few 
years,  into  the  self-study  of  navigation,  having  gone  through 
"Raper's"  and  "Node's"  and  many  other  textbooks;  but  J 
have  never  mastered  it,  owing,  first,  to  the  failure  of  every- 
body, until  now,  to  make  this  subject  sufficiently  clear  in 
the  explanation  of  its  theory,  and  also  to  the  fact  that 
none  of  them  give  sufficient  examples  for  a  student  to 
familiarize  himself  thoroughly  with  each  step.  I  am  learning 
under  your  system.  Your  work,  I  think,  is  more  perfect  and 
intelligible  than  anything  that  has  heretofore  been  published. 

A.  J.   MOXHAM, 

Mem.ber,  New  York  Yacht  Club 
THOROUGH  AND  ABLE  INSTRUCTION 

Having  just  completed  a  Course  of  study  in  Ocean  Naviga- 
tion and  received  my  Diploma,  I  feel  that  a  few  words  of 
appreciation  are  due  the  International  Correspondence  Schools 
for  their  efforts  in  my  behalf  as  one  of  their  pupils. 

The  fact  that  I  was  able  to  pass  through  this  Course  in 
the  comparatively  short  time  of  a  little  over  6  months  I 
attribute  entirely  to  the  thorough  and  able  manner  in  which 
all  subjects  are  treated  and  to  the  earnest  efforts  on  the 
part  of  the  Instructors  to  encourage,  explain,  and  advise  on 
any  deficiency  they  may  note  in  the  student's  work. 
J.  S.  Crogh.\n, 

Boatswain,  U.  S.  Navy 

13 


Nrm  fnrk  Nautiral  (EoUpg? 
Npw  fork,  N.  ^. 

International  Correspondence  Schools, 
Scranton,  Pa. 
Gentlemen:  It  has  been  my  pleasure 
during  the  past  week  to  carefully  read 
thoroughly  your  three  textbooks  on  "Navi- 
gation and  Nautical  Astronomy."  I  feel  it 
obligatory  to  write  to  you  for  the  purpose  of 
expressing  my  extremely  high  opinion  of  said 
work.  I  cannot  understand  how  it  could  be 
improved.  It  is  masterly  in  every  detail, 
yet  is  so  clearly  and  concisely  written  that  it 
is  within  the  comprehension  and  assimilation 
of  the  average  lay  student.  I  take  off  my 
hat  to  the  author  of  the  books,  whoever  he 
may  be. 

Howard  Patterson.  Principal 


EXPLANATIONS  FULL  AND  CLEAR 

Your  Ocean  Navigation  Course  is  an  excellent  one,  all 
explanations  and  statements  being  very  full  and  clear. 
*  *  *  Before  I  took  up  this  Course,  I  tried  to  study  naviga- 
tion from  Bowditch's  "Practical  Navigator,"  but  soon  gave 
it  up  on  account  of  its  confusing  technicality  to  one  not 
having  a  mathematical  foundation  such  as  is  provided  in 
your  Course.  Carl   I.  Ostrom, 

Quartermaster,  U.  S.  Navy 

MOST  SATISFACTORY  TREATISE  ON  THE  SUBJECT 

I  have  gone  over  the  Lake  Navigation  Course  very  care- 
fully, and  will  say  that,  without  doubt,  it  is  the  most  satis- 
factory treatise  on  the  subject  that  could  be  compiled. 
The  work  reveals  a  master  hand,  and,  as  a  whole,  furnishes 
the  most  thorough  and  masterly  education  that  could  be 
devised  for  the  mariner  on  the  Great  Lakes,  who  stands 
greatly  in  need  of  such  an  education,  but  to  whom  it  has 
heretofore  been  inaccessible. 

Capt.   Frank  Henrich,  Nautical  Expert, 

In  charge   Branch   Hydrographic  Office,  1001   Torry  Bldg. 

Duluth,  Minn. 

THOROUGH  AND  CONCISE 

After  thoroughly  perusing  the  textbooks  on  Navigation 
and  Nautical  Astronomy  of  the  International  Correspond- 
ence Schools,  I  can  conscientiously  say  that  they  are  the 
most  thorough  and  comprehensive  work  on  the  subject  I 
have  ever  seen,  and,  therefore,  I  can  and  will  recommend 
them  to  all  my  friends  who  desire  to  take  a  Course  in  Naviga- 
tion. E.  Greths, 

Chief  Mate  S.  S.  "Francis  H.  Legget," 
Formerly  Teacher  of  Navigation  at  San  Francisco,  Cal. 

COULD  NOT  READ  NOR  WRITE  ENGLISH 

Sewerin  Falk,  U.  S.  S.  ''Kentucky,"  care  of  Postmaster, 
New  York  City,  enrolled  in  the  I.  C.  S.  Ocean  Navigation 
Course  while  a  seaman  in  the  United  States  Navy  and  unable 
to  read  nor  write  English.  He  studied  the  Course  with  the 
aid  of  a  dictionary.  Now  he  not  only  can  read  and 
write  English  but  has  had  his  salary  doubled,  in  a  better 
position  than  when  he  enrolled.  He  holds  a  Diploma  for  the 
Ocean  Navigation  Course.  In  a  letter  to  the  Schools, 
Mr.  Falk  has  written:  "It  is  beyond  mv  power  to  express 
my  heartfelt  gratitude  toward  the  Schools  for  the  thorough 
instruction  and  careful  corrections  given  to  me ;  and  for  the 
interest  they  have  taken  in  helping  me  along.  It  is  with 
great  pleasure  I  recommend  the  I.  C.  S  to  every  man  and 
woman  that  desire  to  better  their  position." 

15 


REFERENCE  VOLUMES  OF  GREAT  VALUE 

When  1  enrolled  in  the  I.  C.  S.,  I  had  only  a  common -sc hoc 
education,  and  was  a  carpenter's  mate,  third  class;  but  no\ 
I  am  carpenter's  mate,  second  class.  The  instruction  an 
books  supplied  by  the  Schools  are  so  thorough  and  clear  tha 
the  student  cannot  fail  to  succeed  in  his  studies,  particular] 
in  the  Navigation  Courses.  I  therefore  recommend  the  l.C.J- 
to  all  seamen  who  wish  to  prepare  themselves  for  a  nautic;) 
examination.  The  Reference  Volumes  are  of  great  value  t 
me  as  a  reference  library.        Sven  J.  Troin, 

U.S.  S.  "Atlanta." 
EASY  TO  LEARN  NAVIGATION 
Thomas  Chantre,  U.  S.  S.  "Des  Moines,"  North  Atlant' 
Squadron,  Sixth  Division,  Cap  Cod    Bay,  in  a  letter  to   i 
Principal  of  the  School  of  Navigation  has  written  the  follow 
ing:   "I  take  pleasure  in  saying  that  the  Navigation  Course 
the  I.  C.  S.  is  the  most  simple  and   thorough  method  for  an; 
ambitious  seaman  to  learn  navigation.     Having  but  a  liniit  ■'< 
common  school  education  to  start  with,  I   have  received   th 
I.  C.  S.  Diploma  with  no  help  outside  of  the  I.  C.  S.  Instn 
tion  Papers.     This  is  a  voucher  of  the  Schools'  guarantee 
teach  any  one  that  will  study.      It  is  my  honest  opinion  tu^ 
their  Course  in  Navigation  cannot  be  other   than  of  grca 
benefit  to  any  sailor  trying  to  lisc  in  his  profession." 
SALARY  INCREASED  100  PER  CENT. 
Peter  J.  Milne,  164:   Bagot   St.,  Kingston,  Ontario,  cov 
hardly  work  division,  in  Arithmetic,  when  he  enrolled  in 
Marine   Engineers'  Course.      Now  he  can  master  the  n. 
difficult  problems  and   has   advanced   from  the  positior 
stationary  fireman  to   that  of  chief  engineer  for  the  Cen, 
Company,    Kingston.      By   means    of     the    Course    he    h 
^•cured  a  first-class  engineer's   certificate. 

PASSED  INSPECTOR'S  EXAMINATION 
John  H.  Frkuenborg,  112  Seventh  Ave.,  North,  Scatt" 
Wash.,  by  studying  the   Lake  Navigation  Cor.rse,  has   be 
:ihle  to  pass  the  inspector's  examination  in  Seattle,  for  mat 
;  iipers  for  steam  vessels.      When  he  enrolled  he  was  a  dev 
and,  soon  securing  a  position  as  mate  at  a  large  increase  i. 
alary. 

EDUCATION  MUCH  IMPROVED  ' 

J.  S.  Drarwooi),  care  of  vStcamer  "Masaha."  Marine  P.  C 
Detroit,  Mich.,  began  studying  the  Lake   Navigation  Cours 
hile  working  as  a  laborer.      As  a  result  of  the   imrcnse 
i.nowledge  Mr.  Dearwood  has,  his  income  has  bten  incrciseS. 
i  Ic  says:   "I  was  only  in  the  fourth  grade  when  I   IcK       'dr. 
md  would  not   take  for  the  I.  C.  S.  Course  twice  wii: 
ic.      I  ha\e  much  improved   in   my  general  ednca: 
(crtainly  would  nrcnuncnil    xunr  Sdinols  f  o  .-in\- <  m. 
an  education. 


THE  LIBRARY 
UNIVERSITY  OF  CALIFORNIA 

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